JP5282512B2 - Chromium film patterning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a patterning method of a chromium film which does not include wet etching treatment process and does not need an exclusive treatment equipment for chlorine gas and enables treatment in an inexpensive device configuration. <P>SOLUTION: The patterning method is constituted so as to have: a chromium film formation process of forming a chromium film 11' on a base 10; a mask material film formation process of forming a mask material film 12', which is not removed on oxygen plasma condition in the following patterning process, on the chromium film 11'; a mask pattern formation process of forming a predetermined mask pattern 12 by patterning the mask material film 12'; a patterning process of heating a stage for film placement to a temperature range of oxygen plasma condition and exposing a part of the chromium film, in which the mask pattern 12 is not formed, to oxygen plasma which does not contain chlorine atom for sublimating and removing it as a chrome oxide. Thereby, a predetermined chromium pattern 11 is obtained. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a chromium film patterning method and a chromium electrode, and in particular, a chromium film patterning method that can be preferably formed as any one or more of a gate electrode, a source electrode, and a drain electrode constituting a semiconductor device, and the same The present invention relates to a chromium electrode obtained by the method.

  Chromium is often used as a constituent material of electrodes constituting thin film transistors and the like. For example, Patent Document 1 below describes a pattern electrode made of a chromium layer as a pattern electrode formed on a semiconductor substrate. In this document, as a method for forming a patterned electrode made of a chromium layer, a method is described in which a resist pattern is formed on a chromium layer formed by sputtering or vapor deposition, and then wet etching is performed with an etchant based on cerium ammonium sulfate. ing.

  Patent Document 2 below describes a composite pattern electrode composed of a silicon film and a chromium film as a gate electrode of a thin film transistor. In this document, as a chromium film patterning method, a resist pattern is formed on a chromium film formed by a sputtering method, and then wet etching is performed using a ceric ammonium nitrate-based etchant. . In this document, it is proposed that plasma treatment using a mixed gas containing chlorine gas and oxygen gas is adopted as a method for removing the metal chromium after wet etching and the residue made of chromium silicide. ing.

  Patent Document 3 listed below describes a composite pattern electrode in which a chromium film and an aluminum film are stacked as a source / drain electrode of a thin film transistor. In this document, as a chromium film patterning method, after a chromium film and an aluminum film are formed by sputtering, wet etching is performed using a resist pattern as a mask, and the residue of chromium and residues such as silicide after the wet etching are removed. As a method, it is proposed to employ a plasma treatment containing oxygen gas.

  In Patent Document 4 below, as a method for patterning a chromium film formed on an insulating substrate by sputtering or the like, a resist pattern is formed on the chromium film, and then wet using a ceric ammonium nitrate based etchant. Etching method and, similar to the above, after wet etching the chromium film so as to remain a predetermined thickness using a ceric ammonium nitrate-based etchant, a mixed gas containing chlorine-based gas and oxygen gas was further used. And a method of dry etching in a plasma atmosphere.

JP 63-114214 A JP 2007-311431 A JP-A-5-283427 JP-A-11-131263

  As described in Patent Documents 1 to 4, patterning of the chromium film is usually performed by wet etching using an etching solution containing a cerium salt, but after the wet etching, chromium is patterned as described above. Residues are the cause of worsening product yield. For this reason, in Patent Documents 2 to 4, a double process of removing such residue by plasma treatment is performed. Further, in the rinsing step after the etching, the pH value becomes weakly acidic and cerium may precipitate, which causes the product yield to deteriorate as described above.

  However, as in the prior art, when chromium is wet-etched in addition to mask pattern etching, dedicated lines consisting of pre-treatment devices, etching treatment devices, post-treatment devices, waste water treatment devices, etc. overlap. In addition to the necessity, the addition of a plasma processing step for removing the residues and the like as described above results in a larger apparatus configuration, which affects production costs. In addition, as described in Patent Documents 2 and 3, in the dry etching process in which plasma treatment is performed with a mixed gas containing a chlorine-based gas, a dedicated facility for treating the chlorine-based gas that is a corrosive gas is required. There is a problem that the apparatus cost is high.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a chromium film patterning method that can be processed with an inexpensive apparatus configuration that does not include a wet etching process. Another object of the present invention is to provide a chromium electrode obtained by such a patterning method.

  The chromium film patterning method of the present invention for solving the above problems is not removed by a chromium film forming step of forming a chromium film on a substrate and oxygen plasma conditions in a subsequent patterning step on the chromium film. A mask material film forming step for forming a mask material film, a mask pattern forming step for patterning the mask material film to form a predetermined mask pattern, and a chromium film in a portion where the mask pattern is not provided are placed. And a patterning step of heating the stage to be in a temperature range of oxygen plasma conditions and exposing to oxygen plasma not containing chlorine atoms to sublimate and remove as chromium oxide.

  According to the present invention, first, chromium is patterned by oxygen plasma containing no chlorine atom in the temperature range of oxygen plasma conditions obtained by heating the stage, thereby efficiently sublimating and removing as chromium oxide. be able to. Second, since the mask material film that is not removed under the oxygen plasma condition in the patterning step is used, the chromium film can be selectively etched, and a fine chromium pattern can be formed. According to the chromium film patterning method having the first and second features, since the wet etching process and the plasma process containing a chlorine-based gas are not performed in the chromium film patterning process, the chromium film is formed with an inexpensive apparatus configuration. Patterning is possible. As a result, there is no reduction in yield due to the influence of residues, precipitates, and the like as in the prior art, and it is not necessary to use an expensive and complicated apparatus, so that the cost reduction in the chromium film patterning process can be realized.

  As a preferred aspect of the chromium film patterning method of the present invention, (1) the mask material film is a photoresist that does not cause a sublimation reaction even when exposed to oxygen plasma in the patterning step, and the patterning of the photoresist is performed by photolithography. (2) The mask material film is a metal material film selected from aluminum, molybdenum, and tantalum that does not cause a sublimation reaction due to oxidation even when exposed to oxygen plasma in the patterning step. The metal material film may be patterned by wet etching, or (3) polysilicon that does not cause a sublimation reaction due to oxidation even when the mask material film is exposed to oxygen plasma in the patterning step. Silicon selected from amorphous silicon, silicon oxide, silicon oxynitride A material film, may be configured to perform a dry etching using a fluorine-based gas patterning of the silicon-based material film.

  As a preferable aspect of the chromium film patterning method of the present invention, the base material may be provided with an intermediate film between the chromium film, a glass material, a heat-resistant plastic material, a silicon oxide material, a silicon nitride material, It is configured to be any one selected from silicon oxynitride materials.

  Further, the present invention provides a chromium electrode, wherein any one or more of a gate electrode, a source electrode, and a drain electrode constituting a semiconductor device is formed by the chromium film patterning method according to the present invention. To do.

  According to the chromium film patterning method of the present invention, since the chromium film can be efficiently and selectively removed as chromium oxide in the chromium film patterning step, a fine chromium pattern can be formed. Therefore, in the chromium film patterning process, neither wet etching nor plasma treatment containing chlorine-based gas is required, and it is possible to pattern the chromium film with an inexpensive apparatus configuration. The yield is not reduced by the influence of the above, and an expensive and complicated device does not have to be used. As a result, cost reduction in the chromium film patterning process can be realized.

  Further, according to the chromium film patterning method of the present invention, a temperature suitable for sublimation removal of the chromium film by oxygen plasma can be realized by a simple means of heating the stage to be mounted, so that the high cost can be achieved with an inexpensive apparatus configuration. A dry process capable of forming an accurate chromium pattern can be provided.

  According to the present invention, a fine and high-precision chromium pattern used for LSI, display electrode wiring, and the like can be formed with a high yield. Therefore, various patterns such as an electrode pattern of a semiconductor device or an organic EL element, a liquid crystal display element, etc. It can be applied as a circuit electrode of a display panel.

  Hereinafter, the chromium film patterning method of the present invention and the chromium electrode obtained by the method will be described in detail, but the present invention is not limited to the form of the drawings or the following embodiments.

[Chrome film patterning method]
FIG. 1 is a schematic process diagram showing an example of the chromium film patterning method of the present invention. FIG. 2 is a schematic configuration diagram showing an example of an apparatus to which the chromium film patterning method of the present invention is applied. As shown in FIG. 1, the chromium film patterning method of the present invention includes a chromium film forming step (FIG. 1 (a)) for forming a chromium film 11 ′ on a substrate 10, and the chromium film 11 ′. Then, a mask material film forming step (FIG. 1B) for forming a mask material film 12 ′ that is not removed under oxygen plasma conditions in a subsequent patterning step (FIG. 1D), and the mask material film 12 ′ is patterned. A mask pattern forming step (FIG. 1C) for forming a predetermined mask pattern 12 and a portion of the chromium film on which the mask pattern 12 is not provided, by heating the stage on which the mask pattern 12 is provided. And a patterning step (FIG. 1D) of sublimation removal as chromium oxide by exposure to oxygen plasma that does not contain chlorine atoms in a temperature range. In addition, as shown in FIG.1 (e), the mask pattern 12 is normally removed after that.

  Hereinafter, each step will be described in detail in the order of steps. First, as shown in FIG. 1A, a chromium film 11 'is formed on the substrate 10 (chrome film forming step).

  The base material 10 is made of a material having heat resistance even when heated to, for example, 100 ° C. or higher and 250 ° C. or lower, preferably 150 ° C. or higher and 200 ° C. or lower, which are requirements for oxygen plasma conditions described later. Further, when the chromium film 11 ′ is formed directly on the substrate 10, it is necessary to be made of a material that does not react with oxygen plasma. Such a material may be an organic substrate or an inorganic substrate.

  Examples of organic base materials include polyethersulfone (PES), polyethylene naphthalate (PEN), polyamide, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, polyether ether ketone, liquid crystal polymer, fluororesin, polycarbonate, and polynorbornene. An organic base material made of a resin, polysulfone, polyarylate, polyamideimide, polyetherimide, or thermoplastic polyimide, or a composite base material thereof can be given. In particular, an organic base material composed of polyimide can be preferably used because it has heat resistance even at a temperature of about 250 ° C. Such an organic substrate may have rigidity, or may be a thin flexible film having a thickness of about 5 μm to 300 μm, for example.

  Examples of the inorganic base material include a base material made of any one of a glass material, a silicon oxide material, a silicon nitride material, silicon oxynitride, and other ceramic materials, and a metal base material such as a SUS base material. For example, the glass substrate may be a glass substrate for liquid crystal displays having a thickness of about 0.05 mm to 3.0 mm.

  The chromium film 11 'is formed by, for example, a sputtering method or a vacuum evaporation method. The thickness of the chromium film 11 'can be set to, for example, about 50 nm to 100 nm. The chromium film 11 ′ is usually provided on the entire surface of the substrate 10, but can also be provided on an arbitrary portion by providing a shielding mask and performing sputtering or vacuum deposition.

  An intermediate film (not shown) may be provided between the base material 10 and the chromium film 11 '. The intermediate film is provided as, for example, an adhesion film, a buffer film (thermal buffer film), a stress relaxation film, an impurity shielding film, and the like, and is, for example, 100 ° C. or higher and 250 ° C. or lower, preferably 150 ° C. or higher, which is a requirement of oxygen plasma conditions described later. It is made of a material having heat resistance even when heated to 200 ° C. or lower, and further made of a material that does not react with oxygen plasma. Specifically, a film made of silicon oxide, silicon oxynitride or the like can be preferably exemplified. The thickness of the intermediate film is arbitrarily set according to its function. In addition, when this intermediate film is provided between the base material 10 and the chromium film 11 ′, the base material 10 does not necessarily have non-reactivity to oxygen plasma as long as it has at least heat resistance. .

  Next, as shown in FIG. 1B, a mask material film 12 'is formed on the chromium film 11' (mask material film forming step).

  The mask material film 12 ′ is made of a material that is not removed under oxygen plasma conditions in a subsequent patterning step (FIG. 1D). By forming the mask material film 12 ′ with such a mask material, as shown in FIG. 1D, only the chromium film 11 ′ can be selectively sublimated and removed as chromium oxide, and the fine chromium pattern 11 is formed. Can be formed. When the mask material film 12 ′ reacts with oxygen plasma in a later patterning process, the mask material film 12 ′ is sublimated and removed, and its edge becomes ambiguous, thereby obtaining a fine and accurate mask pattern 12. The patterning accuracy of the chromium film may be reduced.

  The constituent material of the mask material film 12 ′ is not particularly limited as long as it is a material that cannot be removed under the oxygen plasma conditions in the subsequent patterning step (FIG. 1D), and various materials can be used. For example, a photoresist, a metal material, and a silicon-based material can be cited. In particular, a metal material and a silicon-based material are materials that do not cause a sublimation reaction due to oxidation even when exposed to oxygen plasma in a patterning process described later. In addition, it is preferable that patterning can be performed by wet etching or dry etching.

  Specifically, (1) when the mask material film 12 ′ is a photoresist, the photoresist is patterned by photolithography. Or (2) when the mask material film 12 ′ is a metal material film selected from aluminum, molybdenum, and tantalum that does not cause sublimation reaction due to oxidation even when exposed to oxygen plasma in the patterning step, Patterning is performed by wet etching. Alternatively, (3) the mask material film 12 ′ is a silicon-based material film selected from polysilicon, amorphous silicon, silicon oxide, and silicon oxynitride that does not cause sublimation reaction due to oxidation even when exposed to oxygen plasma in the patterning step. In this case, the silicon-based material film is patterned by dry etching using a fluorine-based gas.

  When the mask material film 12 ′ is a photoresist that does not cause a sublimation reaction even if it is exposed to oxygen plasma in a patterning step to be described later, a commercially available photoresist can be used arbitrarily, and conventionally known means such as spin coating can be used. Can be formed. Such a photoresist is usually not removed under oxygen plasma conditions in a patterning process described later. Therefore, if the mask material film 12 ′ is patterned to form a predetermined mask pattern 12 and then exposed to oxygen plasma in a patterning process described later, only the chromium film 11 ′ can be selectively sublimated and removed. Although the thickness of the resist is not particularly limited, it is usually formed with a thickness of about 1 μm.

  When the mask material film 12 ′ is the above-described metal material film, each metal material film can be formed by sputtering or vacuum deposition. Such a metal material film is not removed under oxygen plasma conditions in a patterning process described later. Therefore, if the mask material film 12 ′ is patterned to form a predetermined mask pattern 12 and then exposed to oxygen plasma in a patterning process to be described later, only the chromium film 11 ′ can be selectively sublimated and removed. Although the thickness of the metal material film is not particularly limited, it is usually formed with a thickness of about 50 nm.

  When the mask material film 12 ′ is the above-described silicon material film, each silicon material film can be formed by sputtering or vacuum deposition. Such a silicon-based material film is not removed under oxygen plasma conditions in a patterning process described later. Therefore, if the mask material film 12 ′ is patterned to form a predetermined mask pattern 12 and then exposed to oxygen plasma in a patterning process to be described later, only the chromium film 11 ′ can be selectively sublimated and removed. Although the thickness of the silicon-based material film is not particularly limited, it is usually formed with a thickness of about 50 nm.

  Next, as shown in FIG. 1C, the mask material film 12 'is patterned to form a predetermined mask pattern 12 (mask pattern forming step).

  The specific means of patterning is selected according to the type of mask material film 12 '. For example, when the mask material film 12 ′ is a photoresist that does not cause a sublimation reaction even if it is exposed to oxygen plasma in a later patterning step, the conventional photolithography (development after exposure using a shielding mask) is performed. Thus, the mask pattern 12 can be formed.

  On the other hand, when the mask material film 12 ′ is a metal material film or silicon-based material film that does not cause sublimation reaction due to oxidation even when exposed to oxygen plasma in a subsequent patterning step, the metal material film or silicon-based material A photoresist is formed on the film by spin coating or the like, the photoresist is patterned by photolithography, and then the metal material film or silicon-based material film in the pattern opening is removed by, for example, wet etching or dry etching. Thus, a mask pattern 12 made of a metal material film or a silicon-based material film is formed.

Wet etching can be preferably applied to the above metal material film, and examples thereof include etchants such as ferric chloride solution, a mixed solution of nitric acid / acetic acid / phosphoric acid, and a mixed solution of perchloric acid / nitric acid. On the other hand, dry etching is advantageous in that a high-resolution pattern can be formed as compared with wet etching. For example, an etchant containing no chlorine and containing a fluorine-based gas such as CF ₄ or SF ₆ and oxygen gas is preferable. Can be mentioned. Such a fluorine-based gas is not a corrosive gas such as a chlorine-based gas, and has an etching rate smaller than that of the chromium film (to the extent that the surface is roughened). The material film can be removed by etching.

  From the viewpoint of patterning a finer chromium film, it is preferable to form a mask pattern 12 made of a silicon-based material film. The reason is that since the silicon-based material film can be formed thinner than the resist or metal material film, the thickness of the mask pattern 12 made of silicon-based material film is set to the thickness of the mask pattern 12 made of resist or metal material film. It can be made thinner. As a result, the chromium film can be patterned finely and accurately under the oxygen plasma conditions described later.

  In particular, from the viewpoint of forming a fine chromium pattern 11 with high accuracy, the mask material film 12 'is preferably a silicon-based material film selected from polysilicon, amorphous silicon, silicon oxide, and silicon oxynitride. Since these silicon-based material films can be patterned with higher accuracy than the above-described metal material film because they can be dry-etched, it is possible to form a fine mask pattern 12 with high accuracy. Among these, a silicon film (polysilicon or amorphous silicon) is preferable because the etching is radical-based etching, and the underlying chromium film is less likely to be damaged. Note that since the silicon oxide film is ionic etching, the underlying chromium film may be damaged (to the extent that the surface is roughened).

  Among the metal material films, aluminum is particularly preferable. This aluminum is cheaper and more common than other metals, and the selection of etchants for other materials can be somewhat difficult.

  Next, as shown in FIG. 1 (d), the stage (see FIG. 2) on which the chromium film 11 'in the portion where the mask pattern 12 is not provided (referred to as an opening portion) is placed is heated. Then, it is exposed to an oxygen plasma containing no chlorine atom, and is sublimated and removed as chromium oxide (patterning step).

  The patterning is performed by sublimating and removing the chromium film 11 ′ in the opening as chromium oxide under predetermined oxygen plasma conditions. The oxygen plasma conditions are (1) a reduced pressure necessary for generating plasma, (2) using oxygen gas not containing chlorine as a raw material gas, and (3) a temperature of 100 ° C. or higher and 250 ° C. or lower, for example. 2 is a requirement, and a patterning target object 23 is placed between the parallel plate electrodes 21 and 22 of the embodiment shown in FIG. 2, and oxygen plasma is generated under these conditions to generate a chromium film. Patterning can be performed.

  The parallel plate electrodes 21 and 22 are disposed opposite to each other in the chamber 24 of the dry etching apparatus 20 having the mode shown in FIG. 2, and have a predetermined frequency (for example, 13) between the electrodes 21 and 22 under predetermined conditions. .56 MHz) can be applied to generate plasma in the space 25 between the electrodes. Although not shown in FIG. 2, the dry etching apparatus 20 includes a gas introduction device that introduces a source gas containing oxygen gas into the device 20, a vacuum exhaust device, an AC power supply, and a control device for them. ing. The electrode 21 disposed on the lower side of the parallel plate electrodes 21 and 22 is used as a stage on which the workpiece 2 is placed. In the present invention, the stage (electrode 21) is provided with a heating device, and the temperature of the oxygen plasma condition (temperature range of 100 ° C. or more and 250 ° C. or less) can be set by heating the stage.

  The reduced pressure condition, which is an oxygen plasma condition, is preferably about 1 Pa or more and 500 Pa or less, for example, and is preferably about 133 Pa described in Examples described later. Moreover, oxygen gas which does not contain chlorine is used for source gas. This source gas may contain helium gas or the like which is an inert gas. The gas flow rate is not particularly limited and is usually about 5 to 15 sccm (standard cubic centimeter per minute) although it depends on the chamber size and the valve opening on the exhaust side. The temperature condition is such that the stage (electrode 21) on which the object 23 is placed is heated to a temperature range of oxygen plasma conditions. The temperature at this time is a temperature measured as the temperature of the object to be processed 23. By setting the object to be processed 23 within the temperature range under the condition where the oxygen plasma is generated, chromium reacts with the oxygen plasma. Sublimates as chromium oxide. Thus, the chromium in the opening portion where the mask pattern 12 is not provided is removed, and the desired chromium pattern 11 can be formed.

  If the above temperature range is set to a temperature range of 150 ° C. or higher and 200 ° C. or lower, chromium is more easily reacted with oxygen plasma, so that the chromium pattern 11 can be formed more efficiently.

  Finally, as shown in FIG. 1E, the mask pattern 12 is removed (mask pattern removal step). This step may be provided as necessary, and may be left depending on the type of the mask pattern 12.

  As described above, according to the chromium film patterning method of the present invention, first, chromium patterning with oxygen plasma not containing chlorine atoms is performed within a temperature range of oxygen plasma conditions by heating the stage, for example. By carrying out in a temperature range of 100 ° C. or more and 250 ° C. or less, sublimation removal can be efficiently performed as chromium oxide. Second, since the mask material film that is not removed under the oxygen plasma condition in the patterning step is used, the chromium film can be selectively etched, and a fine chromium pattern can be formed. According to the chromium film patterning method having the first and second features, since the wet etching process and the plasma process containing a chlorine-based gas are not performed in the chromium film patterning process, the chromium film is formed with an inexpensive apparatus configuration. Patterning is possible. As a result, there is no reduction in yield due to the influence of residues, precipitates, and the like as in the prior art, and it is not necessary to use an expensive and complicated apparatus, so that the cost reduction in the chromium film patterning process can be realized.

  Further, according to the chromium film patterning method of the present invention, a temperature suitable for sublimation removal of the chromium film by oxygen plasma can be realized by a simple means of heating the stage to be mounted, so that the high cost can be achieved with an inexpensive apparatus configuration. An accurate dry process can be provided.

[Chromium electrode]
The chromium electrode of the present invention is used as one or more of a gate electrode, a source electrode, and a drain electrode constituting a semiconductor device, and the chromium electrode is formed by the chromium film patterning method according to the present invention. It is characterized by. Therefore, a fine and high-precision chromium electrode pattern used for LSI and display electrode wiring can be formed with a high yield, so that it can be used as an electrode pattern of a semiconductor device or a circuit of various display panels such as an organic EL element and a liquid crystal display element. It can be applied as an electrode. Note that, as a mode of a semiconductor device including a chromium electrode, a bottom gate type thin film transistor and a top gate type thin film transistor will be described below as representative examples. However, it is needless to say that the present invention is not limited to only those modes. .

  FIG. 3 is a schematic cross-sectional view showing an example of a thin film transistor using a chromium film formed by the patterning method of the present invention as a gate electrode or the like. FIG. 3A is a bottom gate type thin film transistor, and FIG. It is a gate type thin film transistor.

  A thin film transistor 30A shown in FIG. 3A is a thin film transistor having a so-called bottom-gate / top-contact structure. The structure includes a base material 31, and a silicon nitride film or a silicon oxide film 32 formed on the base material 31. A gate electrode 33 formed on the silicon nitride film or silicon oxide film 32, a gate insulating film 34 formed on or covering the gate electrode 33, and a gate insulating film 34. And a source electrode 36 and a drain electrode 37 formed on the semiconductor layer 35 so as to be spaced apart from each other. Reference numeral 39 denotes a protective layer. Note that a thin protective film (not shown) may be provided on the semiconductor layer 35 to prevent damage during electrode formation. In this bottom gate / top contact structure, the semiconductor layer 35 is usually amorphous silicon.

  In this thin film transistor 30A, the gate electrode 33 is a chromium film formed by the patterning method of the present invention.

  A thin film transistor 30B illustrated in FIG. 3B is a thin film transistor having a so-called top gate / top contact structure, and includes a base material 31 and a silicon nitride film or a silicon oxide film 32 formed on the base material 31. The semiconductor layer 38 (source side diffusion film 38s, channel film 38c and drain side diffusion film 38d) formed on the silicon nitride film or silicon oxide film 32, and the source side diffusion film 38s and drain side diffusion of the semiconductor layer 38. A gate insulating film 34 formed to have a contact hole portion on the film 38d, a source electrode 36 and a drain electrode 37 formed in the contact hole portion and connected to the source side diffusion film 38s and the drain side diffusion film 38d, respectively; A gate electrode 33 formed on the gate insulating film 34 directly above the channel film 38c. That. Reference numeral 39 denotes a protective layer.

  In this thin film transistor 30B, the gate electrode 33, the source electrode 36, and the drain electrode 37 are chromium films formed by the patterning method of the present invention.

  The thin film transistor 30A illustrated in FIG. 3A can be manufactured as follows as an example. First, a silicon nitride film 32 is formed by sputtering or the like on a base material 31 made of, for example, polyethersulfone (PES), and the patterning method according to the present invention (see FIG. 1) is performed on the silicon nitride film 32. A gate electrode 33 made of a predetermined chromium pattern is formed. Next, after forming an insulating film made of, for example, silicon oxide so as to cover the gate electrode 33 by vacuum deposition or the like, the insulating film is patterned to form a gate insulating film 34. Next, a silicon semiconductor layer 35 is formed by selectively depositing, for example, amorphous silicon by sputtering or the like using a mask at a predetermined portion on the gate insulating film 34, or covering the gate insulating film 34. Then, for example, an amorphous silicon film is formed by sputtering or the like and then patterned to form a silicon semiconductor layer 35 having a predetermined pattern. Next, for example, an aluminum film is formed by vacuum deposition or the like so as to cover the silicon semiconductor layer 35, and then the aluminum film is patterned and spaced apart so as not to contact each other on the silicon semiconductor layer 35. 36 and the drain electrode 37 are formed. Thus, the thin film transistor 30A can be manufactured.

  The thin film transistor 30B illustrated in FIG. 3B can be manufactured as follows as an example. First, a silicon nitride film 32 is formed on a base material 31 made of, for example, polyethersulfone (PES) by sputtering or the like, and amorphous silicon is formed on the silicon nitride film 32 by sputtering or the like. The formed amorphous silicon is subjected to laser annealing treatment as necessary to form polysilicon, and after forming a mask pattern made of, for example, silicon oxide on the polysilicon, ion implantation is performed, and each part of the semiconductor layer 38 made of polysilicon is formed. The source side diffusion film 38s, the channel film 38c, and the drain side diffusion film 38d are used. If there is a portion that has become amorphous silicon by ion implantation, laser annealing is performed again as necessary to recrystallize. Next, after forming an insulating film made of, for example, silicon oxide so as to cover the semiconductor layer 38 by vacuum deposition or the like, the insulating film is patterned to form a gate insulating film 34 on the channel film 38c, A contact hole is formed on the side diffusion film 38s and the drain side diffusion film 38d. Next, after forming a chromium film on the gate insulating film 34 and the contact hole portion, the gate electrode 33 and the source electrode 36 each having a predetermined chromium pattern are formed by the patterning method according to the present invention (see FIG. 1). And a drain electrode 37 are formed. Thus, the thin film transistor 30B can be manufactured. In addition, you may perform a high pressure steam process etc. as needed.

  According to such a chromium electrode of the present invention, a fine and high-precision chromium pattern used for LSI or display electrode wiring can be formed with a high yield. It can be applied as a circuit electrode of various display panels.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, this invention is not limited to a following example.

Example 1
A PES substrate having a thickness of 0.1 mm and a size of 50 mm × 50 mm was used as the sample base material 10, and a silicon nitride film having a thickness of 300 to 500 nm was formed on the substrate as an intermediate film having a thermal buffering function by an RF magnetron sputtering method. . A chromium film 11 ′ having a thickness of 100 nm was formed on the silicon nitride film by RF magnetron sputtering. Next, a 100 nm thick mask material film 12 ′ made of silicon oxide is formed on the chromium film 11 ′ by RF magnetron sputtering, and then a 1200 nm thick photoresist is formed on the mask material film 12 ′. The photoresist was formed by spin coating, and the photoresist was patterned by photolithography to form a desired resist pattern (not shown in FIG. 1) on the chromium film 11 ′. The patterning was performed by exposure and development using a shielding mask in which a predetermined shielding pattern was formed on a glass substrate. The obtained resist pattern is a pattern in which lines having a thickness of 1 μm and a width of 10 μm are arranged in parallel at a pitch of 10 μm.

Next, such an object to be processed was placed in the chamber 24 shown in FIG. 2, and the silicon oxide film exposed at the opening where the resist pattern was not provided was dry etched. The dry etching at this time is performed by using a mixed gas of CF ₄ : O ₂ = 9: 1 as an etching gas and supplying the mixed gas into the atmosphere at a flow rate of 100 sccm, and at RF 500 W, 10 Pa, about 1 min. It was done on condition. The obtained mask pattern 12 is a pattern in which lines having a thickness of 0.1 μm and a width of 10 μm are arranged in parallel at a pitch of 10 μm. The silicon oxide film was removed by such dry etching, and the chromium film was exposed at the opening.

  Next, the target object 23 placed in the chamber 24 was subjected to oxygen plasma treatment. In the oxygen plasma treatment, a reduced pressure atmosphere of 133 Pa into which oxygen gas is introduced and the stage as the lower electrode 21 in the chamber 24 is heated to set the temperature of the object to be treated 23 to 150 ° C. This was performed by applying 500 W of power at a frequency of 13.56 MHz between the plate electrodes 21 and 22. The oxygen plasma generated under these conditions reacted with the chromium film exposed at the opening, and the chromium film was sublimated and removed as chromium oxide. Finally, the mask pattern 12 on the chromium film was removed by dry etching similar to that described above, and a chromium pattern 11 in which lines having a thickness of 0.1 μm and a width of 10 μm were arranged in parallel at a pitch of 10 μm could be formed.

(Example 2)
In Example 1, a mask material film made of aluminum was formed instead of a mask material film made of silicon oxide, and the mask material film was patterned except that it was wet-etched with a mixed solution of nitric acid / acetic acid / phosphoric acid. A chromium pattern was formed in the same manner as in Example 1. However, in Example 2, compared to Example 1, the mask pattern obtained by over-etching when the mask material film is wet-etched is likely to have a side cut or the like, and the patterning accuracy may be lowered. , It may be slightly unsuitable for high-definition patterning (about 5 μm or less).

(Example 3)
In Example 1, a mask material film made of molybdenum was formed instead of a mask material film made of silicon oxide, and the mask material film was patterned by wet etching with a mixed solution of perchloric acid and nitric acid. In the same manner as in No. 1, a chromium pattern was formed. However, also in this Example 3, as compared with Example 1, the mask pattern obtained by over-etching when the mask material film is wet-etched is likely to have a side cut or the like, and the patterning accuracy may be lowered. Therefore, it may be slightly unsuitable for high-definition patterning (about 5 μm or less).

Example 4
In Example 1, instead of the mask material film made of silicon oxide, a mask material film made of polysilicon was formed, and the mask material film was patterned by dry etching similar to silicon oxide. A chromium pattern was formed in the same manner as described above. The patterning accuracy of this Example 4 was equivalent to that of Example 1.

(Example 5)
In Example 1, in place of the mask material film made of silicon oxide, a mask material film made of photoresist was formed, and the mask material film was patterned by photolithography in the same manner as in Example 1 except that chromium was used. A pattern was formed. However, in this Example 5, compared with the mask material film made of the metal film or the inorganic film used in Examples 1 to 4 above, the photoresist itself has the side edge of the mask pattern receded by the ashing effect, and the patterning accuracy deteriorates. Therefore, when compared in Examples 1 to 5, it may be somewhat unsuitable for high-definition patterning.

(result)
From the results of Examples 1 to 5, it was possible to dispense with wet etching and a chlorine-based gas processing apparatus in the chromium film patterning step. In particular, when the silicon material film is dry-etched as a mask material film as in the chromium pattern film patterning method shown in the first and fourth embodiments, the mask material film is patterned because the dry etching accuracy of the mask material film is high. The resolution of photolithography performed at the time can be maintained, and as a result, a chromium pattern with high patterning accuracy is obtained. On the other hand, when the wet etching is performed using a metal material film such as aluminum as a mask material film as in the chromium film patterning method shown in the second and third embodiments, depending on the accuracy when the mask material film is wet etched. As a result, the patterning accuracy of the chromium film was determined. Further, in the case of using a photoresist as a mask material film as in the chromium film patterning method shown in Example 5, the limit of the patterning accuracy of the chromium film is about 10 μm.

  In addition, as a result of comparing Examples 1 to 5 with conventional examples (patterns described in the above-mentioned patent documents) in which chromium film patterning is performed by wet etching, in Examples 1 to 5, the influence of yield deterioration due to precipitates. There was no. In particular, high-definition patterning of the chromium film was achieved when the mask material film was dry-etched.

It is typical process drawing which shows an example of the patterning method of the chromium film | membrane of this invention. It is a typical block diagram which shows an example of the apparatus which applies the patterning method of the chromium film | membrane of this invention. It is typical sectional drawing which shows the example of the thin-film transistor which used the chromium film formed by the patterning method of this invention as a gate electrode etc., (A) is a bottom gate type thin film transistor, (B) is a top gate type thin film transistor. It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Base material 11 Chrome pattern 11 'Chrome film 12 Mask pattern 12' Mask material film 20 Dry etching apparatus 21 Electrode (stage)
22 electrode 23 object 24 chamber 25 space 30A, 30B thin film transistor 31 base material 32 silicon nitride film or silicon oxide film 33 gate electrode 34 gate insulating film 35 semiconductor layer (amorphous silicon)
35a Semiconductor layer (polysilicon)
35b Semiconductor layer (amorphous silicon)
36 Source electrode 37 Drain electrode 38 Semiconductor layer 38c Channel film 38s Source side diffusion film 38d Drain side diffusion film 39 Protective film

Claims (4)

A chromium film forming step of forming a chromium film on the substrate;
On the chromium film, a mask material film forming step for forming a mask material film that is not removed under oxygen plasma conditions in a later patterning step;
A mask pattern forming step of patterning the mask material film to form a predetermined mask pattern;
A patterning step of heating the stage on which the mask pattern is not provided to a temperature range of oxygen plasma conditions by heating the stage on which the mask pattern is placed, and exposing to oxygen plasma not containing chlorine atoms to sublimate and remove as chromium oxide; , have a,
The mask material film, patterning method of the chromium film even when exposed to oxygen plasma in the patterning step, characterized in polysilicon or amorphous silicon der Rukoto not cause sublimation reaction by oxidation. The chromium film patterning method according to claim 1, wherein the mask material film is patterned by dry etching using a fluorine-based gas. The base material may be any one selected from a glass material, a heat-resistant plastic material, a silicon oxide material, a silicon nitride material, and a silicon oxynitride material, in which an intermediate film may be provided between the chromium film and the base material. Item 3. The chromium film patterning method according to Item 1 or 2 . The organic base material having heat resistance even when the base material is heated to 150 ° C or higher and 200 ° C or lower, and the temperature range of the oxygen plasma condition is 150 ° C or higher and 200 ° C or lower . Chromium film patterning method.

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