JP2009134273A - Pattern formation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern formation method capable of plotting a photosensitive material for an ultraviolet ray in a pattern with high throughput by a mask-less direct plotting exposure device having an irradiating light source being an h-line in a main wavelength. <P>SOLUTION: The pattern formation method comprises: a step of forming, on a substrate, a first photosensitive material of low sensitivity to the h-line of the main wavelength irradiated from the mask-less direct plotting exposure device but of high sensitivity to energy line including the ultraviolet light ; a step of forming a second photosensitive material of high sensitivity on the first photosensitive material to the h-line of the main wavelength; a step of plotting a second pattern by using the mask-less direct plotting exposure device to the second photosensitive material; a step of developing the second photosensitive material; a step of collectively exposing the second photosensitive material and the first photosensitive material formed with the second pattern; a step of separating the second photosensitive material; and a step of forming an objective first pattern by developing the first photosensitive material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photolithography method. More specifically, the present invention relates to a photolithographic method. More specifically, a laser is focused on a second photosensitive material formed on a first photosensitive material according to a pattern to be exposed, and a second pattern is directly formed. Drawing and developing, using the second pattern as a mask, batch exposing the first photosensitive material, peeling off the second photosensitive material and developing the first photosensitive material The present invention relates to a pattern forming method for forming a first pattern as a solder resist on a substrate.

  The printed wiring board is a component that constitutes an electronic circuit by mounting electronic components such as resistors and capacitors and connecting the components with wiring. An electronic component is mounted on the soldering land of the conductor circuit pattern. The conductor circuit portion excluding the soldering land is covered with a solder resist as a permanent protective film.

  The solder resist prevents solder from adhering to unnecessary portions when soldering electronic components, and prevents the conductor circuit portion from being directly exposed to air and being oxidized. The solder resist also has a role of improving electrical characteristics and maintaining insulation between conductors.

  A material that covers a part of the surface of a workpiece with a desired pattern and applies the following treatment to only the uncovered part is called a resist. It is mainly a photo-curing resin. Other resists include a solder resist for soldering, a plating resist for plating, and an etching resist for etching.

  Conventionally, in order to form patterns on various wiring boards such as printed wiring boards, semiconductors, and liquid crystals, a photosensitive liquid resist or dry film resist is formed on the substrate, and then exposed through a photomask. I went.

  In the production of wiring boards, it is expected that high-precision wiring can be provided at low cost and with short delivery times, but depending on the type of board, there are many cases of high-mix low-volume production and high-variety variable-volume production. Manufacturing a mask has led to an increase in cost and a delay in delivery time. For this reason, there is a strong demand for maskless exposure that can simultaneously realize all kinds of variables, high accuracy, and low cost.

  Such maskless direct drawing exposure technology does not require the production of a photomask, so it not only saves mask manufacturing equipment costs and material costs, but also shortens the mask manufacturing time (lead time) for printing. A wiring board can be manufactured. Further, the maskless direct drawing exposure technique is characterized in that the exposure can be performed while correcting the position by detecting the distortion and deflection amount of the substrate, so that highly accurate alignment is possible.

  As a first method for performing maskless exposure, there is a method of directly drawing a pattern on a substrate by scanning laser light using a laser beam having a large output and a polygon mirror. This method is good at drawing a relatively rough pattern over a large area, and can be configured with a simple and inexpensive apparatus.

  As a second method for performing maskless exposure, as described in Patent Document 1 (Japanese Patent Laid-Open No. 11-320968), a two-dimensional spatial light modulator such as liquid crystal or DMD (Digital Micro-Mirror Device) is used. There is a method in which a two-dimensional pattern is generated using, and this pattern is directly drawn on a substrate by a projection lens. According to this method, a fine pattern can be drawn. In the two-dimensional drawing which is a feature of such two-dimensional light modulation, it is possible to further improve the drawing speed by increasing the light intensity. Patent Document 2 (Japanese Patent Laid-Open No. 2002-182157) and Patent Document 3 (Japanese Unexamined Patent Application Publication No. 2004-157219) proposes an optical intensity increasing optical system.

  However, in the first method, it is difficult to draw a large area with high definition, and if it is attempted to reduce the throughput, a high-power laser beam is required, the apparatus becomes expensive, and the running cost increases.

  The durability and life of the two-dimensional light modulator used in the second method depend not only on the intensity of incident light but also on the wavelength. Therefore, in the light intensity region applied to the maskless exposure technique, the malfunction rate and defect occurrence rate of the light modulation element increases or the life until the fatal failure occurs decreases in the ultraviolet light region (less than 400 nm) with a short incident wavelength. Tend to. Therefore, when ultraviolet light is incident on the two-dimensional light modulation element, the light intensity is limited in exchange for a longer exposure time, or visible light (400 to 800 nm) or red having a longer wavelength than ultraviolet light. External light (over 800 nm) needs to be incident.

  On the other hand, a mercury lamp, which is a light source used in an exposure apparatus using a conventional mask, has a strong wavelength spectrum distribution for i-line (365 nm), h-line (405 nm), and g-line (436 nm). Metal halide lamps frequently used for exposure of liquid resists also mainly have specifications for efficiently emitting light near the i-line. The photosensitive material used in the exposure technology for wiring formation is designed from the viewpoint of mass productivity and workability so that the shorter the wavelength of the irradiated light, the higher the sensitivity and the lower the sensitivity in the visible light region. Has been. In general, good patterning is possible when exposed to i-rays, which are mercury emission lines.

  When performing maskless exposure, it is not impossible to use a mercury lamp as a light source, but it is difficult to obtain exposure illumination light with high efficiency and high directivity from the mercury lamp.

  That is, long-wavelength visible light is more suitable for maskless exposure light modulation optical systems than short-wavelength ultraviolet light. Due to this problem, it has been difficult to achieve both high throughput and high definition of exposure.

  In order to improve exposure throughput in maskless exposure, a resist suitable for a maskless exposure apparatus using a visible light source has been developed. These resists have a photosensitive region in the visible light to infrared light region, and can maintain a good exposure throughput even when maskless exposure is performed. However, these maskless exposure-only resists having a visible light source cannot use the yellow room used in the case of resists sensitive to ordinary ultraviolet light, so a dark room or a red room is required, and a substrate in a mass production site. The manufacturing conditions need to be changed, and the material price is higher than that of a general-purpose material having a photosensitive region in ultraviolet light, and the running cost is increased.

  In addition to the resist developed exclusively for the visible light source, there are photosensitive materials having a photosensitive region in the visible light region. For example, a silver salt photographic photosensitive material containing a silver halide emulsion layer (hereinafter referred to as JP-A-2007-242371) or JP-A-2004-221564 (JP-A-2004-221564). , A silver halide material) is capable of uniform pattern exposure with a low exposure even in a maskless exposure apparatus using a visible light source. However, since this photosensitive material is an electromagnetic shielding material and a conductive material for touch panels, it cannot be used as a solder resist that is an insulating material for printed wiring boards.

  In addition, the sensitivity of the solder resist is particularly lower than that of other photosensitive materials such as a plating resist and an etching resist, and the exposure throughput is significantly lower than that of a maskless direct drawing exposure apparatus using a semiconductor laser as a light source.

  As electronic components become smaller and higher in density, the pad dimensions and pitch dimensions of soldered parts also become smaller year by year. In the solder resist exposure process, the resolution and alignment accuracy of the pattern formed between the pads are important. It becomes. Therefore, it is desired to apply maskless exposure to the solder resist exposure process.

If sufficient curing is not obtained in the solder resist exposure step, the surface of the solder resist is liable to be affected by the developer in the development step after exposure, and the performance required for the printed wiring board may not be obtained. When a printed wiring board is produced by increasing the exposure amount, not only the accuracy of the exposure pattern is remarkably lowered but also the time required for the production process is increased, which has an adverse effect on the productivity. Accordingly, there is a need for an exposure method capable of forming a pattern with high alignment accuracy and high resolution even with a low exposure amount.
JP-A-11-320968 JP 2002-182157 A JP 2004-157219 A JP 2007-242371 A JP 2004-221564 A

  In any of the conventional techniques (Patent Documents 1 to 5), a pattern is formed by exposing a solder resist, which is a photosensitive material having low sensitivity to a light source that emits visible light of a maskless exposure apparatus, at a high throughput. The technology is not described.

  Accordingly, an object of the present invention is to provide a pattern forming method with high accuracy and high exposure efficiency that satisfies the required level of cost reduction and short delivery time in maskless exposure.

  In order to achieve the above object, the present invention forms a first photosensitive material on a substrate, which has low sensitivity to visible light and high sensitivity to energy rays containing ultraviolet light or near ultraviolet light. Forming a film, forming a second photosensitive material having higher sensitivity to visible light than the first photosensitive material on the first photosensitive material, and forming the second photosensitive material on the first photosensitive material. A first exposure step of drawing a second pattern using a maskless direct drawing exposure apparatus that irradiates the photosensitive material with exposure light comprising the visible light, and the drawn second photosensitive material. A first developing step for forming a second pattern by processing with a developing solution; and the ultraviolet light or near ultraviolet light for the second photosensitive material formed on the first photosensitive material. Irradiating energy rays containing the second pattern to the second pattern A second exposure step in which the first pattern is exposed by transferring to one photosensitive material, and the second photosensitive material is removed from the first photosensitive material exposed in the second exposure step. A pattern forming method comprising: a peeling step for removing; and a second developing step for forming the first pattern by treating the first photosensitive material left in the peeling step with a developer. It is.

  According to the present invention, in the pattern forming method, the first photosensitive material is formed of a photosensitive solder resist, and the second photosensitive material has a photosensitive material layer composed of a silver halide layer. Features.

  That is, in a pattern forming method for forming a first pattern on a first photosensitive material having low sensitivity to visible light used in a maskless direct drawing exposure apparatus, It is divided into two stages: pattern drawing on a second photosensitive material that is highly sensitive to visible light exposure light formed on the substrate, and photocuring by batch exposure of energy rays to the first photosensitive material. Thus, the time required for pattern drawing is greatly reduced.

  Thus, in order to improve the low sensitivity of the first photosensitive material used as the solder resist to the visible light used in the maskless direct drawing exposure apparatus, for example, a silver halide material is used. It has been found that it is preferable to form a second photosensitive material having high sensitivity to the visible light exposure light on the first photosensitive material. This is because, as described above, a yellow room cannot be used for the second photosensitive material having a high sensitivity to the exposure light of the visible light, so a dark room or a red room is required, and in a mass production site. Since it is also necessary to change the substrate manufacturing conditions, it is out of the concept of those skilled in the art.

  In addition, when the material which does not have photosensitivity to the light of wavelength 450nm or more as disclosed in patent document 6 (Unexamined-Japanese-Patent No. 2003-77350) is used as the 2nd photosensitive material in this invention, for example. Can use the yellow room.

  The first photosensitive material and the second photosensitive material are sequentially formed on the substrate, and the first photosensitive material has a low sensitivity to a light source of a maskless direct drawing exposure apparatus. On the other hand, a photosensitive material exhibiting high sensitivity is selected as the second photosensitive material. The second photosensitive material includes a non-photosensitive transparent film as a support, and it is further desirable that the transparent film has a release treatment surface subjected to a release treatment. The transparent film supports a photosensitive material layer (hereinafter referred to as a high-sensitivity photosensitive layer) having high sensitivity to visible light of the second photosensitive material, and a developer for the high-sensitivity photosensitive layer is the first. In order to prevent the photosensitive material from coming into contact with each other, the mutual diffusion between the high-sensitivity photosensitive layer and the first photosensitive material is prevented, thereby preventing contamination and preventing fluctuations in the sensitivity of the photosensitive material. Have a role to play. Further, the release treatment surface has a role of facilitating peeling of the second photosensitive material in a later step and reducing damage to the first photosensitive material that occurs when peeling. Due to the nature of the first photosensitive material, the release treatment surface is not essential. A second photosensitive material having a layer structure in the order of a release treatment surface, a transparent film, and a high-sensitivity photosensitive layer is disposed on the substrate on which the first photosensitive material is formed. It is desirable that the film can be formed at 70 ° C. or lower so as to be in contact with the photosensitive material. This is to prevent thermal curing of the first photosensitive material. Moreover, it is desirable that the release treatment surface and the transparent film are transparent (transmittance of total light (visible light to ultraviolet light) is 90% or more).

  The maskless exposure apparatus directly draws a pattern in which the negative and positive are reversed from the desired exposure pattern with respect to the light source of the maskless exposure apparatus. Since the second photosensitive material has high sensitivity, the exposure efficiency can be significantly improved as compared with the case where the first photosensitive material having low sensitivity is drawn directly. In particular, the effects of the present invention can be greatly expected for the exposure of solder resist. The solder resist is used for applying or laminating the entire pattern of the printed wiring board excluding the soldered portion for mounting the electronic component. Therefore, when the negative solder resist is exposed by the method of the present invention, a pattern reversed from the desired pattern covering the entire surface of the substrate is drawn, so that the drawing area can be reduced, and the pattern drawing of the maskless direct drawing exposure apparatus can be performed. Such time can be further shortened.

  The first photosensitive material preferably has a sensitivity twice or more lower than that of the second photosensitive material with respect to visible light used as a light source of a maskless exposure apparatus. The sensitivity in this case indicates the degree of curing of the photosensitive material. The second photosensitive material is cured by a maskless exposure apparatus, and it is desirable that photocuring of the first photosensitive material is started by a light irradiation amount that is equal to or greater than the optimum exposure amount for pattern drawing. This is because the first photosensitive material is not cured at the time of pattern drawing by the maskless exposure apparatus. In other words, the exposure light of the visible light used as the light source of the maskless exposure apparatus can be described. Therefore, the present invention is suitable only for a photosensitive material having a very low sensitivity.

  The second photosensitive material needs to have a characteristic of causing a change in transmittance by pattern exposure and development processing. That is, at the time after film formation and before exposure, the transmittance is 30% or more and 70% or less with respect to the light source of the maskless exposure apparatus, and after exposure and development, the total light transmittance needs to be 10% or less. is there. The sensitivity of the second photosensitive material itself is defined by the amount of change in transmittance that changes before and after drawing with a maskless exposure apparatus. When the second photosensitive material is developed, and the defined pattern has a characteristic of shielding the illumination light, the pattern of the second photosensitive material and the first photosensitive material are simultaneously irradiated on the entire surface, The second photosensitive material becomes a photomask, and the pattern directly drawn by the maskless exposure apparatus and the pattern in which the negative and positive are reversed are drawn on the first photosensitive material. By adhering the second photosensitive material to the low-sensitivity first photosensitive material, which is the layer to be processed, exposure can be performed without causing optical misalignment such as diffraction. It is also possible to eliminate the influence of oxygen inhibition, which is a factor that lowers the sensitivity of the material.

  A pattern can be formed on the first photosensitive material by developing the low-sensitivity first photosensitive material after peeling off the second photosensitive material. Since the pattern is drawn by a maskless exposure apparatus, an improvement in resolution can be expected.

  By applying the pattern forming method of the present invention, pattern drawing with a maskless exposure apparatus can be performed with high accuracy and high exposure efficiency that satisfies the required level of cost reduction and short delivery time.

  Moreover, in the exposure process of the solder resist used for the printed wiring board, it is possible to perform highly accurate alignment exposure while maintaining the electrical characteristics of the resist, and to greatly shorten the pattern drawing time.

  Hereinafter, embodiments of the pattern forming method according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

  First, an outline of an embodiment according to the present invention will be described with reference to FIGS. 1 and 2.

  The pattern forming method according to the present invention includes a step [1] of forming a first photosensitive material 3 on a substrate 5 and a transparent film 2a having a release treatment surface 2b on the surface opposite to the release treatment surface 2b. A high-sensitivity photosensitive layer (silver salt photographic photosensitive material containing a silver halide emulsion layer) 1 having a higher sensitivity to visible light than the first photosensitive material 3 is formed on the second photosensitive material. 6 is formed, the second photosensitive material 6 is laminated on the first photosensitive material 3 to form the high-sensitivity photosensitive layer 1, and the main wavelength is h-line ( An exposure process [4] for directly drawing a pattern on the high-sensitivity photosensitive layer 1 with a maskless direct drawing exposure apparatus (not shown) that irradiates the blue semiconductor laser 7 having a wavelength of 405 nm), and the high-sensitivity photosensitive layer 1 Step [5] of forming a drawing pattern by development, and a drawing pattern formed on the high-sensitivity photosensitive layer 1 Exposure step [6] for simultaneously exposing the photosensitive layer 1 ′, the second photosensitive material 6 and the first photosensitive material 3 simultaneously, the drawing pattern 1 ′ of the high-sensitivity photosensitive layer 1 and the second photosensitive material A stripping step [7] for removing 6 and a reverse pattern (target cured solder resist pattern) 3 ′, which reverses the drawing pattern 1 ′ by developing the first photosensitive material 3, are formed on the substrate 5. It has process [8].

  In FIG. 2, reference numeral 4 denotes a conductor portion on the substrate 5. Reference numeral 7 denotes a blue semiconductor laser in which the main wavelength of visible light emitted from the first exposure light source of the maskless direct drawing exposure apparatus used in the exposure step [4] is h-line (wavelength 405 nm). 8 is an energy beam that is emitted from the second irradiation light source used in the exposure step [6] and contains 350 to 450 nm ultraviolet light or near ultraviolet light with an intensity of 1% to 100% of the total emitted energy. Show.

  As a maskless direct drawing exposure apparatus (not shown), for example, a blue semiconductor laser that emits visible light is used as a first exposure light source, and a laser beam is scanned by using a laser beam having a large output and a polygon mirror to scan the substrate. A device for directly drawing a pattern on a substrate, or a device for generating a two-dimensional pattern using a two-dimensional spatial light modulator such as a liquid crystal or DMD (Digital Micro-Mirror Device) and drawing the pattern directly on a substrate with a projection lens Etc. are considered.

  Next, each step will be described in detail.

  The first photosensitive material 3 used in the present invention is a negative i-line photosensitive material used for manufacturing a wiring board, and mainly in the process of manufacturing a wiring board, from 350 to 450 nm of ultraviolet light to near ultraviolet light. Irradiated with light and used for photolithography. Although this photosensitive material 3 can be considered in various ways depending on its purpose and application, a solder resist that covers a conductor circuit portion other than a soldering land on a printed wiring board as a permanent protective film uses a blue semiconductor laser as a first exposure light source. Since the exposure efficiency is particularly poor for drawing with a maskless exposure apparatus, the effects suitable for the present invention tend to be easily obtained.

  FIG. 3 shows a curing behavior (exposure) of the high-sensitivity photosensitive layer 1 and the first photosensitive material 3 used in the pattern forming method according to the present invention when irradiated with a blue semiconductor laser beam whose main wavelength is h-line (wavelength 405 nm). It is a figure which shows one Example of the relationship between the quantity and the film thickness of the photosensitive material after image development. The photosensitive material that can be used as the first photosensitive material 3 is a material that starts to be cured by a light irradiation amount that is equal to or higher than the exposure amount that the highly sensitive photosensitive layer 1 is completely cured. At the time of pattern drawing of the high-sensitivity photosensitive layer 1 in the exposure step [4], when the illumination light reaches the first photosensitive material film 3 through the transparent film 2a and the release treatment surface 2b provided as the intermediate layer. If the sensitivity of the first photosensitive material 3 is close to the sensitivity of the high-sensitivity photosensitive layer 1, the first photosensitive material 3 is also exposed and cured.

  In the present invention, a pattern in which the negative and positive are reversed with respect to a desired pattern finally formed on the first photosensitive material 3 is applied to the high-sensitivity photosensitive layer 1 in a maskless exposure apparatus in the exposure step [4]. In order to perform drawing, when the high-sensitivity exposure layer 1 is exposed, if the first photosensitive material 3 is similarly cured, there is a possibility that a desired pattern cannot be obtained. Accordingly, in the exposure step [4], it is necessary that the exposure amount at the point where the first photosensitive material 3 starts to be cured is larger than the exposure amount at the point where the curing of the high-sensitivity photosensitive layer 1 is completed. In the high-sensitivity photosensitive layer 1 and the first photosensitive material 3, the exposure wavelength (main wavelength is h-line) emitted from the first exposure light source of the maskless exposure apparatus before pattern drawing by the maskless exposure apparatus. It is desirable that the sensitivity has a difference of twice or more, and the larger the difference is, the more suitable for the present invention.

  The form of the first photosensitive material 3 used in the present invention may be either a dry film form or a liquid form. In any case, the first photosensitive material 3 can be appropriately formed on the surface of an object to be exposed such as a wiring board by a predetermined method. good. The method for forming the first photosensitive material 3 on the substrate in the step [1] is not particularly limited. For example, if the first photosensitive material 3 is a film, a lamination method, a vacuum If the first photosensitive material 3 is in a liquid state such as a laminating method, a spray coating method, a roll coating method, a spin coating method or the like can be used. The film thickness of the first photosensitive material 3 suitable for the present invention after film formation is in the range of 2 micrometers to 100 micrometers, and the minimum processing dimension is about 1 micrometer. The photosensitive material 3 used here is preferably a photosensitive material mainly composed of an epoxy resin, an epoxy acrylate resin, or the like. It goes without saying that photosensitive compositions other than those exemplified here can be used depending on the structure and application of the object to be exposed.

  In order to form the second photosensitive material 6 in the step [2], the high-sensitivity photosensitive layer 1 is formed on the transparent film 2a. However, this method is not particularly limited. If it is a film, it is a laminating method, a vacuum laminating method or the like, and if the high-sensitivity photosensitive layer 1 is liquid, a spray coating method, a roll coating method, a spin coating method or the like can be used. As the transparent film 2a, a polymer film such as polyethylene terephthalate or polypropylene can be used. As the high-sensitivity photosensitive layer 1, in the exposure step [4], for example, if direct writing is performed by a maskless exposure apparatus using a blue semiconductor laser as a first exposure light source, h line (wavelength 405 nm) is formed after film formation. It is necessary to fix the max pattern 1 ′ by causing a change in light transmittance so as to shield all rays after exposure and development. In addition, if the first photosensitive material 3 is a negative type, regardless of the type, either a negative type or a positive type can be applied to the high-sensitivity photosensitive layer 1. In the negative photosensitive material, the part irradiated with light is cured and the non-irradiated part is dissolved by development, whereas in the positive photosensitive material, the part irradiated with light is dissolved by development and the non-irradiated part is dissolved. Harden. Regardless of the reactive type of the high-sensitivity photosensitive layer 1, a maskless exposure apparatus in which the mask pattern 1 ′ is inverted with respect to the desired pattern 3 ′ to be formed on the first photosensitive material 3 in the exposure step [4]. Draw with.

  There is also a method of forming a transparent film 2a on the first photosensitive material 3 and further forming a high-sensitivity photosensitive layer 1 thereon. However, it is preferable to prepare the second photosensitive material 6 separately and deposit the film on the first photosensitive material 3 because damage to the first photosensitive material 3 can be reduced. However, the physical properties of the first photosensitive material 3 are not limited to these.

  In the step [3], the method for forming the laminated film 6 on the first photosensitive material film 3 is not particularly limited, and examples thereof include a laminating method and a vacuum laminating method. Furthermore, in order to prevent the first photosensitive material 3 from being thermally cured, the temperature during film formation is preferably 70 ° C. or lower, but this is limited depending on the physical properties of the first photosensitive material 3. is not.

  In the exposure step [4], a pattern is directly drawn on the high-sensitivity photosensitive layer 1 using a maskless exposure apparatus. Thereafter, in step [5], the unexposed portion of the high-sensitivity photosensitive layer 1 is dissolved using a developer corresponding to the high-sensitivity photosensitive layer 1, thereby obtaining a drawing mask pattern 1 '. At this time, the transparent film 2 a and the first photosensitive material 3 must be in close contact so that the developer does not come into contact with the first photosensitive material 3. What is necessary is just to use what was suitable for the kind of developing solution according to the kind of photosensitive material used for the high sensitivity photosensitive layer 1. FIG.

  The second irradiation light source used in the exposure step [6] is a light source capable of irradiating energy rays 8 containing ultraviolet light or near ultraviolet light of 350 to 450 nm with an intensity of 1% to 100% of the total emitted energy. Specifically, a metal halide lamp, a discharge lamp such as a low to very high pressure mercury lamp, a xenon lamp, a halogen lamp, a semiconductor laser light source, or the like is preferable. In particular, a semiconductor laser with easy control of irradiation energy or a metal halide lamp that is inexpensive and easy to maintain is suitable, and any light source that can uniformly irradiate a large area may be used. Furthermore, it can be selected in consideration of power consumption, controllability of irradiation amount, etc. according to the purpose of use and the photosensitive material, and a plurality of these can be used in combination.

  Since the second light irradiation in the exposure step [6] does not require alignment, it can be performed in a state where the object to be exposed is not fixed or during movement. Specifically, irradiation may be performed in the process of transporting the object to be exposed. Therefore, the exposure time required for the second irradiation does not affect the throughput.

  In the exposure step [6], the entire surface of the first photosensitive material 3 is cured by batch irradiation using the drawing pattern 1 ′ as a mask, and then in the peeling step [7], the release treatment surface 2b, the transparent film 2a, and the drawing pattern. 1 'is peeled off. The method for peeling is not particularly limited. In step [8], the reversal pattern 3 ′ is formed on the substrate 5 by, for example, dissolving the unexposed portion of the first photosensitive material 3 using a developer corresponding to the first photosensitive material 3. obtain. If necessary, heat curing and post-heating are performed to accelerate the desired desired pattern 3 ′.

  In the above description, the second photosensitive material 6 has a three-layer structure including the high-sensitivity photosensitive layer 1, the transparent film 2a, and the release treatment surface 2b. Of course, only the sensitive photosensitive layer 1 may be directly formed on the first photosensitive material, drawn and removed.

  Next, examples according to the present invention will be described. An alkali-soluble negative liquid photosensitive solder resist (SR7200G, manufactured by Hitachi Chemical Co., Ltd.) as the first photosensitive material 3 is placed on a double-sided copper-clad laminate 5 having a thickness of 0.5 mm and a thickness of about 25 micrometers. The material to be exposed was prepared by coating. Further, a high-sensitivity photosensitive layer containing silver iodobromide grains containing 5 mol% of silver iodide (average grain size is 1 μm or less in terms of sphere equivalent diameter) so that the volume ratio with the gelatin solution is 0.6. 1 was applied to a polyethylene terephthalate (PET) film 2a having a thickness of 100 micrometers so that the adhesion amount of silver was 0.3 mol / m 2 to form a second photosensitive material 6. This second photosensitive material 6 was laminated at 50 ° C. on the solder resist layer.

  In the exposure step [4], the high-sensitivity photosensitive layer 1 is exposed at an exposure amount of 10, 20, and 30 mJ / cm 2 in a maskless exposure apparatus having a blue semiconductor laser 7 whose main wavelength is h-line (wavelength 405 nm) as a first light source. I drew a pattern. In this embodiment, the exposure value measured by an ultraviolet light meter UV-M03A manufactured by Oak Manufacturing Co., Ltd. is used. Then, after developing with an alkaline solution and fixing the pattern with an acid solution in step [5], the pattern forming portions of the solder resist film and the high-sensitivity photosensitive layer 1 are simultaneously and uniformly made in the exposure step [6]. Irradiated with light. In this example, the entire surface of the solder resist layer was cured with an exposure dose of 800 mJ / cm 2 using a semiconductor laser light source that irradiates energy rays 8 containing ultraviolet light or near ultraviolet light of 350 to 450 nm. . Then, in the peeling step [7], the pattern portion of the high-sensitivity photosensitive layer 1 and the PET film are peeled off from the solder resist layer, and in step [8], development is performed with a 1% by weight, 30 ° C. aqueous sodium carbonate solution. A pattern 3 ′ in which the negative and the positive were reversed with respect to the pattern drawn by the less exposure apparatus was obtained.

The appearance of the via opening pattern formed in the solder resist layer was observed. The results are shown in Table 1. Here, Examples 1 to 3 are obtained by changing only the exposure amount of the laser beam whose main wavelength is h-line by the maskless exposure apparatus, and Comparative Examples 1 to 3 are not provided with the high-sensitivity photosensitive layer 1. A case where a via pattern is directly drawn on a solder resist layer by a maskless exposure apparatus while changing the exposure amount of laser light having a main wavelength of h-line is shown. The data size of the drawing pattern diameter means the data size of the via opening in the test pattern data stored in the maskless exposure apparatus. In Examples 1 to 3 and Comparative Examples 1 to 3, the via opening diameter actually opened in the solder resist layer when the pattern data of φ70 μm was exposed was examined.

  As shown in Example 1, when the exposure amount was 10 mJ / cm 2, the actual opening diameter was slightly small due to insufficient exposure. This indicates that even when the high-sensitivity photosensitive layer 1 is patterned, the silver deposition amount is insufficient for pattern formation of the solder resist layer at this level of exposure. However, as in Example 2, when the exposure amount was 20 mJ / cm 2, a sufficient actual aperture diameter was obtained with no defects (close to a perfect circle in the case of a via shape). Even when the exposure amount was 30 mJ / cm 2, a good pattern shape was shown (Example 3). However, when the exposure amount was 40 mJ / cm 2 or more, it was impossible to draw a pattern on the high-sensitivity photosensitive layer 1 itself due to overexposure. . Therefore, the exposure amount of 20 mJ / cm2 is optimal when only the actual size of the opening is viewed, but it is advantageous that the exposure amount is larger with respect to the degree of hardening of the silver halide material (developer resistance, remaining film thickness, etc.). In consideration of the fact, an exposure amount in the range of 20 to 30 mJ / cm 2 is suitable. That is, it is characterized in that the exposure amount by the maskless exposure apparatus is controlled to be in the range of 20 to 30 mJ / cm 2, for example.

  On the other hand, when the solder resist is exposed only by a maskless exposure apparatus that irradiates a laser beam having a main wavelength of h-line without using a silver halide layer as shown in the comparative example, the solder resist layer has the main wavelength h. Since the sensitivity to the line is low, the solder resist was not cured at all at the exposure amount of 30 mJ / cm 2 shown in Comparative Example 1, and was completely dissolved in the development process. In addition, when the exposure amount is increased to 500 mJ / cm 2 as in Comparative Example 2, the solder resist becomes hardened, and the pattern size has a data size of 500 μm, but an opening is formed in the case of a large via shape. In the case of a small via shape such as 70 μm, the shape collapsed due to development due to insufficient exposure, and the desired pattern shape could not be maintained. Further, in order to obtain an actual aperture diameter equivalent to the case where the high-sensitivity photosensitive layer 1 is present without defects, the solder resist layer has low sensitivity to the main wavelength h-line, so that it can be seen from Comparative Example 3. , An exposure amount of 800 mJ / cm 2 was necessary.

  As described above, according to the embodiment of the present invention, it is possible to reduce the exposure amount of a blue semiconductor laser whose main wavelength for pattern drawing by a maskless exposure apparatus is h-line to 20 to 30 mJ / cm 2, In addition, a desired pattern can be obtained by previously reversing the drawing pattern in the maskless exposure apparatus to negative / positive. Further, according to the embodiment of the present invention, the time required for pattern drawing on the high-sensitivity photosensitive layer 1 by the maskless exposure apparatus is shortened to 1/15 to 1/10 as compared with the case of drawing directly on the solder resist layer. Is possible.

  Another embodiment will be described. As the first photosensitive material 3, an alkali-soluble negative liquid photosensitive solder resist (PSR-4000 AUS300 manufactured by Taiyo Ink Manufacturing Co., Ltd.) and a double-sided copper clad laminate 5 having a thickness of 0.8 mm (Hitachi Chemical Industry Co., Ltd.) It was applied to MCL-E-67) manufactured so as to have a film thickness of about 25 micrometers to prepare an object to be exposed. Further, a second photosensitive material 6 (CUHE-100E manufactured by Konica Minolta MG Co., Ltd.) obtained by coating a polyethylene terephthalate (PET) film 2a having a thickness of 100 micrometers with a gelatin solution containing silver halide as the high-sensitivity photosensitive layer 1. ) Was laminated at 50 ° C. on the solder resist layer.

  In the exposure step [4], the high-sensitivity photosensitive layer 1 is exposed at 20, 30, and 40 mJ / cm 2 in a maskless exposure apparatus having a blue semiconductor laser 7 whose main wavelength is h-line (wavelength 405 nm) as a first light source. I drew a pattern. In this embodiment, the exposure value measured by an ultraviolet light meter UV-M03A manufactured by Oak Manufacturing Co., Ltd. is used. In step [5], development was performed with an alkaline solution (CDM-681 manufactured by Konica Minolta MG Co., Ltd.), and the pattern was fixed with an acid solution (CFL-881 manufactured by Konica Minolta MG Co., Ltd.). Thereafter, in the exposure step [6], the solder resist film and the pattern forming portion of the high-sensitivity photosensitive layer 1 were simultaneously irradiated with light uniformly in the plane. In this example, an ultra high pressure UV (Ultra Violet) lamp (USH-manufactured by Ushio Electric Co., Ltd.) that irradiates energy rays 8 containing ultraviolet light or near ultraviolet light of 350 to 450 nm for curing the solder resist layer. 500D), the entire surface was irradiated with an exposure amount of 500 mJ / cm2. Then, in the peeling step [7], the pattern portion of the high-sensitivity photosensitive layer 1 and the PET film are peeled off from the solder resist layer, and in step [8], development is performed with a 1% by weight, 30 ° C. aqueous sodium carbonate solution. A pattern 3 ′ in which the negative and the positive were reversed with respect to the pattern drawn by the less exposure apparatus was obtained.

The appearance of the via opening pattern formed in the solder resist layer was observed. The results are shown in Table 2. Here, Examples 4 to 6 are obtained by changing only the exposure amount of the laser beam having the main wavelength of h-line by the maskless exposure apparatus, and Comparative Examples 4 to 7 are not provided with the high-sensitivity photosensitive layer 1. A case where a via pattern is directly drawn on a solder resist layer by a maskless exposure apparatus while changing the exposure amount of laser light having a main wavelength of h-line is shown. The data size of the drawing pattern diameter means the data size of the via opening in the test pattern data stored in the maskless exposure apparatus. In Examples 4 to 6 and Comparative Examples 4 to 7, the via opening diameter actually opened in the solder resist layer when the pattern data of φ150 μm was exposed was examined.

  As shown in Example 4, when the exposure amount was 20 mJ / cm 2, the actual aperture diameter was slightly small due to insufficient exposure. This indicates that even when the high-sensitivity photosensitive layer 1 is patterned, the silver deposition amount is insufficient for pattern formation of the solder resist layer at this level of exposure. However, as in Example 5, when the exposure amount was 30 mJ / cm 2, a sufficient actual aperture diameter was obtained with no defects (close to a perfect circle in the case of a via shape). Even when the exposure amount was 40 mJ / cm 2, a good pattern shape was shown (Example 6). However, when the exposure amount was 50 mJ / cm 2 or more, the opening diameter of the high-sensitivity photosensitive layer 1 was increased due to overexposure, and the solder was accordingly accompanied. The opening diameter of the resist layer was also increased. Therefore, the exposure amount of 30 mJ / cm 2 is optimal when only the actual size of the opening is viewed, but it is advantageous that the exposure amount is larger with respect to the degree of curing (developer resistance, remaining film thickness, etc.) of the high-sensitivity photosensitive layer 1. In view of this, an exposure amount in the range of 30 to 40 mJ / cm 2 is suitable. That is, it is characterized in that the exposure amount by the maskless exposure apparatus is controlled to be in the range of 30 to 40 mJ / cm 2, for example.

  On the other hand, when the solder resist is exposed only by a maskless exposure apparatus that emits laser light having a main wavelength of h-line without using the high-sensitivity photosensitive layer 1 as shown in Comparative Examples 4 to 7, the solder resist layer is Since the sensitivity to h-rays at the main wavelength is low, the solder resist was not cured at all at the exposure amount of 30 mJ / cm 2 shown in Comparative Example 4, and was completely dissolved in the development process. In addition, when the exposure amount is increased to 1000 mJ / cm 2 as in Comparative Example 5, the solder resist becomes hardened, and the pattern size has a data size of 500 μm. In the case of a small via shape such as 150 μm, the shape collapsed due to development due to insufficient exposure, and the desired desired pattern shape could not be maintained. As shown in Comparative Example 6, when an exposure dose of 1500 mJ / cm 2 was irradiated, a via shape with a data size of 150 μm could be opened, but the actual size of the opening diameter was the same as when the high-sensitivity photosensitive layer 1 was present without any defects. Couldn't get. When the exposure amount was further increased as in Comparative Example 7, the aperture diameter was reduced due to overexposure. In the absence of the high-sensitivity photosensitive layer 1, the aperture diameter becomes the largest at an exposure amount of 1500 mJ / cm 2, which is almost the same value as the aperture diameter in Example 1. That is, there is a feature that the resolution of the solder resist layer is improved by performing exposure using the high-sensitivity photosensitive layer 1.

  As described above, according to the embodiment of the present invention, it is possible to reduce the exposure amount of a blue semiconductor laser whose main wavelength is h-line for pattern drawing by a maskless exposure apparatus to 30 to 40 mJ / cm 2, In addition, a desired pattern can be obtained by previously reversing the drawing pattern in the maskless exposure apparatus to negative / positive. Further, according to the embodiment of the present invention, it is possible to reduce the time required for pattern drawing on the high-sensitivity photosensitive layer 1 by the maskless exposure apparatus to 1/20 as compared with the case of drawing directly on the solder resist layer. It is.

It is process drawing which shows one Embodiment of the pattern formation method which concerns on this invention. [1] to [8] are schematic cross-sectional views in the order of steps [1] to [8] shown in FIG. It is a figure which shows the hardening behavior at the time of the blue semiconductor laser beam irradiation whose main wavelength of the high sensitivity photosensitive layer and 1st photosensitive material used for the pattern formation method concerning this invention is h line | wire. It is process drawing which shows one Embodiment of the pattern formation method which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High sensitive photosensitive layer 1 'Photosensitive part, Drawing pattern after 1 hardening 2a Transparent film 2b Release processing surface 3 First photosensitive material 3' Photosensitive part, 3 Reverse pattern after hardening 4 Conductor part 5 Substrate 6 Second Photosensitive material 7 h-line semiconductor laser light source 8 Lamp light source

Claims (10)

A film forming step of forming a first photosensitive material on the substrate having a low sensitivity to visible light and a high sensitivity to energy rays containing ultraviolet light or near ultraviolet light;
Forming a second photosensitive material having higher sensitivity to visible light than the first photosensitive material on the first photosensitive material;
A first exposure step of drawing a second pattern using a maskless direct drawing exposure apparatus that irradiates the exposure light composed of the visible light to the second photosensitive material;
A first developing step of processing the drawn second photosensitive material with a developer to form a second pattern;
The second photosensitive material formed on the first photosensitive material is collectively irradiated with energy rays containing the ultraviolet light or near ultraviolet light, and the second pattern is formed on the first photosensitive material. A second exposure step of transferring to the photosensitive material and exposing the first pattern;
A peeling step of removing the second photosensitive material from the first photosensitive material exposed in the second exposure step;
And a second developing step of forming the first pattern by treating the first photosensitive material left in the peeling step with a developing solution.   2. The pattern forming method according to claim 1, wherein the first photosensitive material is formed of a photosensitive solder resist, and the second photosensitive material has a photosensitive material layer composed of a silver halide layer.   In the second exposure step, the second photosensitive material formed on the first photosensitive material is uniformly irradiated in-plane with an energy line containing the ultraviolet light or near ultraviolet light. The pattern forming method according to claim 1, wherein the pattern forming method is a pattern forming method.   3. The pattern forming method according to claim 1, wherein the reaction type of the first photosensitive material is a negative type, and the reaction type of the second photosensitive material is a negative type.   3. The pattern forming method according to claim 1, wherein the reaction type of the first photosensitive material is a negative type, and the reaction type of the second photosensitive material is a positive type.   The second photosensitive material has a laminated structure having a photosensitive material layer that is highly sensitive to visible light formed on a support and a release treatment surface that is subjected to a release treatment on the opposite surface. The pattern forming method according to claim 1, wherein the pattern forming method is a pattern forming method.   The pattern forming method according to claim 6, wherein the release treatment surface can be formed at 70 ° C. or less on the substrate on which the first photosensitive material is formed.   The pattern forming method according to claim 6, wherein the support and the release treatment surface are formed of a non-photosensitive and transparent material.   In the second exposure step, when the energy beam containing the ultraviolet light or near ultraviolet light is collectively irradiated, the second pattern formed on the second photosensitive material in the first development step is a mask. The pattern forming method according to claim 1, wherein the pattern forming method serves as a pattern. In the first exposure step, when the second pattern is drawn on the second photosensitive material, the first photosensitive material is exposed to exposure light composed of visible light that is not cured by being exposed to light. The pattern forming method according to claim 1, wherein an irradiation amount with respect to the second photosensitive material is controlled.

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