JP2007251063A - Wiring pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring pattern forming method capable of excellently forming a wiring pattern on a substrate by using a chemical amplification type resist which contains an alkali-soluble resin. <P>SOLUTION: While forming a base layer on a substrate, after patterning the base layer in a specified shape, the wiring pattern forming method comprises: a depositing process for depositing a metal layer on the substrate wherein the base layer is formed; an application process for forming a resist film by applying a chemical amplification type resist material containing alkali-soluble resin onto the metal layer; an exposure process for exposing this resist film selectively; an after-exposure heating process for carrying out heat processing to the resist film by heating the base layer; a development process for forming a resist pattern by carrying out the processing procedure of the resist film; and a patterning process patterning the metal layer by carrying out wet etching of the metal layer via the resist pattern. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wiring pattern forming method for forming a wiring pattern composed of wiring composed of a base layer and a metal layer on a substrate.

  For example, a wiring pattern on which an integrated circuit such as an IC or LSI is mounted may be formed on a substrate used for various devices such as a liquid crystal display or a head mounted on a printer. Such a wiring pattern is generally formed using a photolithography method. Specifically, a metal film made of a metal material is formed on a substrate, and then a resist film is formed on the metal film by applying a resist, exposing and developing, and the metal film is formed through the resist film. A wiring pattern is formed by etching, for example, wet etching. In forming such a wiring pattern, a resist containing an alkali-soluble resin is often used (see, for example, Patent Document 1). This is because, in general, the resolution is remarkably higher than that of other rubber negatives and the like, and a wiring pattern can be formed with high accuracy.

  However, when a resist film is formed with such a resist, for example, when the metal film is wet etched, the resist film is slightly peeled off, and the width of each wiring constituting the wiring pattern becomes narrower than a desired width. There is a problem that it ends up. Such a problem is particularly likely to occur when a chemically amplified resist is used. When a resist film is formed using a chemically amplified resist, a resist heat treatment, for example, a post-exposure heat treatment (PEB) in which the resist is heat-treated after exposure is performed. In order to form a resist film satisfactorily, it is necessary to apply such heat treatment uniformly to the entire resist, but temperature management is extremely difficult. Since heat treatment such as post-exposure heat treatment is performed by, for example, heating the substrate with a hot plate, it is difficult to make the resist heating temperature constant between the central portion and the peripheral portion of the substrate. The current situation is that the whole cannot be heat-treated uniformly.

  If the resist is not heat-treated under the predetermined conditions, the end face of the resist after development is not formed perpendicular to the surface or the resist film is peeled off as described above, resulting in the width of the wiring. The problem that becomes thin will arise.

Japanese Patent Laid-Open No. 07-201722

  In view of such circumstances, it is an object of the present invention to provide a method for forming a wiring pattern that can satisfactorily form a wiring pattern on a substrate using a chemically amplified resist containing an alkali-soluble resin. .

A first aspect of the present invention that solves the above problem is that a wiring pattern composed of a wiring composed of a base layer having a predetermined width and a metal layer formed on the base layer is formed on a substrate by a photolithography method. A method of forming a wiring pattern, wherein the underlayer is formed on a substrate and the underlayer is patterned into a predetermined shape, and then the metal layer is formed on the substrate on which the underlayer is formed. A film forming step, a coating step of applying a chemically amplified resist material containing an alkali-soluble resin on the metal layer to form a resist film, an exposure step of selectively exposing the resist film, A post-exposure heating step in which the resist film is heat-treated by heating a base layer; a development step in which the resist film is developed to form a resist pattern; Certain metal layer forming method of the wiring pattern; and a patterning step of patterning the metal layer by wet etching.
In the first aspect, the resist film can be heat-treated satisfactorily, and the resist pattern used for patterning the metal layer is formed with extremely high accuracy. For this reason, it is possible to form the wiring pattern on the substrate with good accuracy with wet etching of the metal layer through the resist pattern.

According to a second aspect of the present invention, the wiring pattern according to the first aspect further includes a pre-exposure heating step of heating the resist film by heating the underlayer before the exposure step. In the formation method.
In the second aspect, the resist pattern is formed more satisfactorily.

According to a third aspect of the present invention, there is provided the wiring pattern forming method according to the first or second aspect, wherein the underlayer is heated by electromagnetic induction heating.
In the third aspect, the underlayer can be selectively and reliably heated.

According to a fourth aspect of the present invention, there is provided the wiring pattern forming method according to the third aspect, wherein the base layer is formed of a material having a specific resistance higher than that of the metal layer.
In the fourth aspect, the underlayer can be selectively and reliably heated, and the resist film can be heat-treated more favorably by the heat.

According to a fifth aspect of the present invention, there is provided the wiring pattern forming method according to the fourth aspect, wherein the underlayer is formed of a material containing a base metal, and the metal layer is formed of a material containing a noble metal. .
In the fifth aspect, by forming the base layer and the metal layer with a predetermined material, the resist film can be further heat-treated and a wiring pattern having excellent electrical characteristics can be formed.

Hereinafter, the present invention will be described in detail based on embodiments.
The wiring pattern forming method of the present invention can be applied when forming a wiring pattern composed of a base layer and a metal layer on a substrate constituting various devices by a lithography method. The present invention will be described by exemplifying a wiring pattern formed on a protective substrate constituting the head. First, a schematic configuration of the ink jet recording head will be described. FIG. 1 is an exploded perspective view of the ink jet recording head, and FIG. 2 is a plan view of FIG. 1 and a cross-sectional view taken along line AA ′.

  As shown in the figure, the flow path forming substrate 10 is made of, for example, a silicon single crystal substrate, and an elastic film 50 made of silicon dioxide having a thickness of about 0.5 to 2 μm is formed on one surface thereof. In the flow path forming substrate 10, pressure generation chambers 12 partitioned by a plurality of partition walls 11 are arranged in parallel. A communication portion 13 is formed on the outer side in the longitudinal direction, and the communication portion 13 communicates with each pressure generation chamber 12 via an ink supply path 14.

On the opening surface side of the flow path forming substrate 10, a nozzle plate 20 having a nozzle opening 21 is fixed by an adhesive or the like. On the other hand, the elastic film 50 is provided on the side opposite to the opening surface of the flow path forming substrate 10 as described above, and the insulator film 55 made of zirconium oxide (ZrO ₂ ) or the like is further formed on the elastic film 50. Are stacked. On the insulator film 55, the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80 are laminated to form the piezoelectric element 300. One end of a lead electrode 90 is connected to each upper electrode film 80 which is an individual electrode of the piezoelectric element 300. The lead electrode 90 extends from the upper electrode film 80 to the insulator film 55 and is electrically connected to a drive circuit described later.

  A protective substrate 30 is bonded onto the flow path forming substrate 10 with an adhesive or the like. The protective substrate 30 is provided with a piezoelectric element holding portion 31 that is a space for protecting the piezoelectric element 300. The protective substrate 30 is provided with a reservoir portion 32 penetrating in the thickness direction. The reservoir portion 32 communicates with the communication portion 13 of the flow path forming substrate 10, and the reservoir portion 32 and the communication portion 13 form a reservoir 100 that serves as a common ink chamber for the pressure generation chambers 12. Further, the protective substrate 30 is provided with a connection hole 33 that penetrates the protective substrate 30 in the thickness direction in a region between the piezoelectric element holding portion 31 and the reservoir portion 32. The lead electrode 90 drawn out from each piezoelectric element 300 extends into the connection hole 33. As the protective substrate 30, it is preferable to use a material substantially the same as the coefficient of thermal expansion of the flow path forming substrate 10, for example, glass, a ceramic material, etc. In this embodiment, the same material as the flow path forming substrate 10 is used. It was formed using a silicon single crystal substrate.

  Further, a drive wiring pattern 210 is formed on the protective substrate 30, and a drive IC 220 for driving the piezoelectric element 300 is mounted on the drive wiring pattern 210. In the present embodiment, the drive IC 220 and the lead electrode 90 are electrically connected via a connection wiring (not shown) made of a conductive wire such as a bonding wire.

  Here, as shown in FIG. 3, the drive wiring pattern 210 is configured by drive wirings 211 having a predetermined width and arranged at predetermined intervals. Each drive wiring 211 is composed of a metal layer 212 and a base layer 213 for ensuring adhesion between the metal layer 212 and the protective substrate 30. The drive wiring pattern 210 composed of such drive wirings 211 is formed by a photolithography method as will be described in detail later.

  On the protective substrate 30, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded. The sealing film 41 is made of a material having low rigidity and flexibility, and one surface of the reservoir portion 32 is sealed by the sealing film 41. The fixed plate 42 is formed of a hard material such as metal. Since the region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with a flexible sealing film 41. Has been.

  Hereinafter, a method of forming the drive wiring pattern 210 formed on the protective substrate 30 constituting such an ink jet recording head will be described with reference to FIGS. 4 to 6 are enlarged sectional views of the surface portion of the protective substrate.

  First, as shown in FIG. 4A, the base layer 213 is formed over the entire surface of the protective substrate 30 by, for example, a sputtering method. Since the base layer 213 is for ensuring the adhesion between the metal layer 212 and the protective substrate 30 as described above, the material may be appropriately determined according to the material of the metal layer 212. It is preferable to use a material having a higher specific resistance than the metal layer 212. Specifically, as the material for the base layer 213, for example, a material containing a base metal such as nickel (Ni) is preferably used. For example, in this embodiment, nickel chrome (NiCr) is used as the material of the base layer 213, and the base layer 213 is formed to have a thickness of about 50 to 100 nm by a sputtering method.

  Next, as shown in FIG. 4B, the base layer 213 is patterned into a predetermined shape. The patterning method of the base layer 213 is not particularly limited. For example, in the present embodiment, the base layer is patterned by a photolithography method. That is, a resist is coated on the underlayer 213, and a resist pattern (not shown) is formed by exposure and development, and the underlayer 213 is patterned into a predetermined shape by etching through the resist pattern. Yes. Note that the base layer 213 is preferably formed with relatively high accuracy. Therefore, it is desirable that the resist pattern used for patterning the base layer 213 be formed with high accuracy by, for example, exposing the resist using a reduction projection exposure apparatus (stepper) or the like.

  Next, as shown in FIG. 4C, a metal layer 212 is formed over the entire surface by, for example, a sputtering method on the protective substrate 30 provided with the base layer 213 patterned in a predetermined shape. Membrane process). Although the material of the metal layer 212 is not particularly limited, it is preferable to use a material with low specific resistance because it constitutes the drive wiring 211, and includes, for example, a noble metal such as gold (Au) or palladium (Pd). Materials. In the present embodiment, gold (Au) is used as the material of the metal layer 212, and the metal layer 212 is formed by sputtering to have a thickness of about 1 μm.

  Next, the metal layer 212 is patterned so as to have a predetermined shape, that is, the same pattern as the base layer 213. First, as shown in FIG. 5A, a resist is applied to the entire surface of the protective substrate 30 to form a resist film 240 (application process). In the present invention, a chemically amplified resist containing an alkali-soluble resin is used as this resist. This resist may be either a negative type or a positive type, but in this embodiment, a positive type resist is used. Next, as shown in FIG. 5B, the resist film 240 is exposed through a predetermined mask material 250 (exposure process). That is, the resist film 240 in a region other than the region where the base layer 213 is formed is exposed. Note that the exposure conditions are not particularly limited, and may be determined as appropriate according to the resist to be used.

  Next, the post-exposure heat treatment (PEB) of the resist film 240 is performed by selectively heating the base layer 213. That is, the post-exposure heat treatment of the resist film 240 is performed by selectively heating the base layer 213 without heating the entire protective substrate 30 (post-exposure heating step). For example, in this embodiment, as shown in FIG. 5 (c), the protective substrate 30 is placed on a table 260 provided with an induction heating coil (not shown), and the dielectric coil is energized in this state, thereby electromagnetic induction. The underlayer 213 is selectively heated by heating. Then, by heating the base layer 213, the heat is transmitted to the resist film 240 through the metal layer 212, and the resist film 240 is subjected to heat treatment. Note that various conditions during heating, such as frequency, may be appropriately determined according to the material of the base layer 213.

  Here, it is important that the post-exposure heat treatment is performed on the unexposed regions 241 of the resist film 240 under uniform conditions. Then, by performing post-exposure heat treatment of the resist film 240 by heating the underlayer 213 as in the present invention, each unexposed region 241 can be reliably heat-treated under uniform conditions. As in this embodiment, it is particularly effective when the post-exposure heat treatment is performed on the protective substrate 30 in which the through holes such as the reservoir portion 32 are formed, that is, the resist film 240 formed on the perforated substrate. is there.

  When the post-exposure heat treatment of the resist film 240 is performed, for example, when the entire substrate is heated with a hot plate or the like as in the prior art, for example, there is a temperature difference due to a difference in heat dissipation between the central portion and the peripheral portion of the substrate. As a result, it is difficult to uniformly heat the entire resist film. When a perforated substrate such as the protective substrate 30 is heated, a similar temperature difference occurs between the region close to the through hole and the region away from the through hole, and the entire resist film is uniformly heated. It is even more difficult.

  However, by performing post-exposure heat treatment of the resist film 240 by selectively heating the base layer 213 without heating the entire protective substrate 30 as in the present invention, there is almost no temperature difference in each part of the resist film. The resist film 240 can be heat-treated at a substantially uniform temperature without being generated. At least each unexposed region 241 of the resist film 240 can be reliably heat-treated at a uniform temperature. Thereby, for example, even when the resist film 240 is underexposed in the exposure step, the underexposure is reliably compensated. In addition, by heating the base layer 213, the resist film 240 can be heat-treated in a relatively short time, so that the adhesion between the resist film 240 and the metal layer 212 is significantly improved. Note that, as described above, since the base layer 213 is formed of a material having high specific resistance, it is heated to a temperature sufficient for the heat treatment of the resist film 240 by electromagnetic induction heating.

  Next, as shown in FIG. 6A, a resist pattern 245 having a predetermined shape is formed by developing the resist film 240 with a predetermined developer (development process). Each end surface 240a of the resist film 240 constituting such a resist pattern 245 is formed substantially perpendicular to the surface of the metal layer 212 (protective substrate 30). That is, in the post-exposure heat treatment process described above, the resist film 240 is subjected to extremely good heat treatment. As a result, the end surfaces 240a of the resist film 240 are formed substantially vertically.

  Here, FIG. 7 shows an SEM image showing the surface state of the resist pattern (resist film) formed by the method of the present invention. FIG. 8 shows an SEM image showing the surface state of a resist pattern (resist film) formed by a conventional method. As shown in FIG. 7, the end face of the resist film formed by the method of the present invention is very well formed substantially perpendicular to the surface of the metal layer, and no resist residue can be confirmed on the surface of the metal layer. There wasn't. On the other hand, as shown in FIG. 8, the end surface of the resist film formed by the conventional method, that is, by heating the entire substrate using a hot plate or the like and heat-treating the resist film after exposure is formed on the surface of the metal layer. On the other hand, it was not formed on a surface perpendicular to the surface, and a resist residue was confirmed in a relatively wide range on the surface of the metal layer. As is apparent from these SEM images, according to the method of the present invention, the resist pattern 245 can be formed extremely well.

  The developer used for developing the resist film 240 is not particularly limited. In the present invention, since a resist containing an alkali-soluble resin is used, it is not necessary to use a chemical solution containing a thinner solvent. For example, a relatively environmentally friendly chemical solution such as hexamethyldisilazane (HMDS) is used. It can be used as a developer.

  Next, as shown in FIG. 6B, the metal layer 212 is patterned into a predetermined shape by wet-etching the metal layer 212 through the resist pattern 245 (patterning step). That is, the metal layer 212 other than the region facing the base layer 213 is removed by wet etching. Thereafter, the resist pattern 245 is removed by ashing or the like, thereby forming the drive wiring pattern 210 including the drive wiring 211 composed of the base layer 213 and the metal layer 212 (see FIG. 3).

  In such a patterning step, the metal layer 212 is satisfactorily formed so that the end surface 212a is substantially perpendicular to the surface of the protective substrate 30 without being inclined. This is because the end surface 240 a of the resist film 240 is formed substantially perpendicular to the surface of the protective substrate 30 as described above. Further, since the adhesion between the resist film 240 and the metal layer 212 is improved by performing the post-exposure heating step, the resist film 240 is not peeled off when the metal layer 212 is patterned. For this reason, the metal layer 212 is hardly side-etched in the patterning process. For example, the pattern width of the metal layer 212 is kept constant even when the etching time is extended to about 1.5 to 2 times the normal etching (just etch) time. Therefore, the metal layer 212 can be patterned with extremely high accuracy without requiring strict management of the etching time.

  Thus, the width of the metal layer 212 is determined by the width of the resist film 240 constituting the resist pattern 245. Therefore, the width of each drive wiring 211 can be substantially widened to reduce the electrical resistance, and the design margin can be widened to increase the density of the drive wiring pattern 210. In addition, since the resist pattern 245 is formed extremely well, occurrence of etching failure or the like of the metal layer 212 can be suppressed, so that the yield can be improved and the cost can be reduced.

  Further, the end surface 212a of the metal layer 212 formed by the method of the present invention, that is, the end surface 211a of the drive wiring 211 is configured by a surface substantially perpendicular to the surface of the protective substrate 30 as described above. Therefore, abnormal leakage due to the shape defect of the drive wiring 211 can be prevented, for example, occurrence of defects such as disconnection can be prevented. Further, since the end surface 211a of the drive wiring 211 is formed substantially vertically and there is no so-called sagging, the drive IC 220 can be reliably mounted. In addition, since the drive wiring pattern 210 is extremely well formed and has good adhesion to the protective substrate 30, even when a polishing process such as a back grinder is performed in the subsequent process, In addition, problems such as peeling of the drive wiring 211 do not occur.

  Furthermore, in the method of the present invention, since the base layer 213 is patterned before the metal layer 212 is patterned, and the metal layer 212 can be patterned with extremely high accuracy, the base layer is formed after the metal layer 212 is patterned. There is no need to further pattern 213. Accordingly, the selection range of the material for the underlayer 213 is greatly expanded. For example, when the underlayer is patterned by wet etching after patterning the metal layer, there is a problem that side etching of the underlayer tends to proceed due to an electrolytic corrosion reaction that occurs between the metal layer and the underlayer. The selection range is limited. However, according to the method of the present invention, the problem of side etching of the underlayer 213 does not occur, so the selection range of the material for the underlayer 213 is greatly expanded.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. For example, in the present embodiment, the method of performing the post-exposure heating process after exposing the resist film has been described. However, the present invention is not limited to this, for example, heating the underlayer before the exposure process. Then, a pre-exposure heating step (pre-baking step) for heating the resist film may be further performed. Even when such a pre-exposure heating step is carried out, for example, by heating the underlayer by electromagnetic induction heating, the resist film can be heat-treated with the heat very well.

  In the present embodiment, the present invention has been described by exemplifying the drive wiring pattern formed on the protective substrate of the ink jet recording head. However, the present invention is not limited to a substrate on which any device such as a semiconductor device is used. It can be employed when forming a wiring pattern.

FIG. 3 is an exploded perspective view illustrating an example of a recording head. 2A and 2B are a plan view and a cross-sectional view of a recording head. It is a schematic sectional drawing which shows the drive wiring pattern which concerns on one Embodiment. It is a schematic sectional drawing which shows the formation process of the drive wiring pattern which concerns on one Embodiment. It is a schematic sectional drawing which shows the formation process of the drive wiring pattern which concerns on one Embodiment. It is a schematic sectional drawing which shows the formation process of the drive wiring pattern which concerns on one Embodiment. It is a SEM image which shows the surface state of the end surface of the resist film which concerns on one Embodiment. It is a SEM image which shows the surface state of the end surface of the resist film which concerns on a prior art.

Explanation of symbols

10 flow path forming substrate, 20 nozzle plate, 30 protection substrate, 40 compliance substrate, 210 driving wiring pattern, 211 driving wiring, 212 metal layer, 213 underlayer, 220 driving IC, 240 resist film, 245 resist pattern, 250 mask material 260 tables

Claims (5)

A wiring pattern forming method for forming a wiring pattern formed on a substrate by a photolithography method by a wiring composed of a base layer having a predetermined width and a metal layer formed on the base layer,
Forming a base layer on the substrate, patterning the base layer into a predetermined shape, and then forming the metal layer on the substrate on which the base layer is formed; and on the metal layer An application step of forming a resist film by applying a chemically amplified resist material containing an alkali-soluble resin, an exposure step of selectively exposing the resist film, and heating the underlayer to form the resist film A post-exposure heating step for heat treatment; a development step for developing the resist film to form a resist pattern; and a patterning step for patterning the metal layer by wet etching the metal layer through the resist pattern; A method of forming a wiring pattern, comprising: 2. The method for forming a wiring pattern according to claim 1, further comprising a pre-exposure heating step of heating the resist film by heating the underlayer before the exposure step. The method for forming a wiring pattern according to claim 1, wherein the underlayer is heated by electromagnetic induction heating. The wiring pattern forming method according to claim 3, wherein the underlayer is formed of a material having a specific resistance higher than that of the metal layer. 5. The method for forming a wiring pattern according to claim 4, wherein the underlayer is formed of a material containing a base metal, and the metal layer is formed of a material containing a noble metal.

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