JP2008153354A - Method for forming organic semiconductor pattern and method for manufacturing semiconductor device - Google Patents

Abstract

An organic semiconductor pattern forming method capable of forming a fine pattern without damaging the organic semiconductor layer.
A mask pattern is formed on a substrate. Next, the organic semiconductor layer 13 is formed on the substrate 1 by film formation from the mask pattern 11. Then, the organic semiconductor layer 13 on the mask pattern 11 is removed by peeling off the mask pattern 11 from the substrate 1, and the organic semiconductor layer 13 formed directly on the substrate 1 in the opening 11 a of the mask pattern 11. Only the portion is left as the organic semiconductor pattern 13a.
[Selection] Figure 1

Description

  The present invention relates to a method for forming an organic semiconductor pattern and a method for manufacturing a semiconductor device, and more particularly to a method for forming a pattern without deteriorating an organic semiconductor material and a method for manufacturing a semiconductor device to which this forming method is applied.

  Thin film transistors are widely used as pixel transistors in electronic circuits, particularly in active matrix flat panel displays.

  Currently, most thin film transistors are Si-based inorganic semiconductor transistors using amorphous silicon or polycrystalline silicon as a semiconductor layer (active layer). Since these processes require heat treatment at high temperature, the substrate is required to have heat resistance.

  On the other hand, an organic thin film transistor using an organic semiconductor can perform a semiconductor thin film serving as an active layer by coating film formation or vapor deposition film formation at a low temperature, which is advantageous for cost reduction, plastics, etc. However, it can be formed on a flexible substrate.

  Here, the following procedures are illustrated as a manufacturing process of a thin film transistor using an organic semiconductor. First, after forming a gate electrode on a substrate, a gate insulating film is formed so as to cover the gate electrode. Next, source / drain electrodes are formed on the gate insulating film, and an organic semiconductor pattern is formed so as to cover them. The organic semiconductor pattern is formed, for example, by vapor deposition from a metal mask as a first example.

  In addition, as a second example of organic semiconductor pattern formation, a resist pattern is formed on a base, an organic semiconductor layer is formed thereon, and then the organic semiconductor layer on the upper portion thereof is etched together with the resist pattern by etching using a resist stripping solution. There is a method of selectively removing the portion by lift-off. Furthermore, as a third example, there is a method of forming a resist pattern after forming an organic semiconductor layer and pattern-etching the organic semiconductor layer using the resist pattern as a mask. Furthermore, as a fourth example, a pattern is formed on the organic semiconductor layer with a destructive agent having the ability to change the characteristics of the organic semiconductor layer, and the conductivity of the organic semiconductor layer portion below the destructive agent is deteriorated to form an insulator. Have been proposed (see Patent Documents 1 and 2 below).

JP 2000-268640 A Special Table 2003-508924

  However, the organic semiconductor pattern forming method described above has the following problems. That is, in the method using the metal mask described as the first example, there is a limit to the fineness of the pattern, and it is difficult to form a pattern with good positional accuracy on a large-area substrate.

  Further, in the second example and the third example, the resist stripping solution used for removing the resist pattern also damages the organic semiconductor layer. Therefore, the leakage current in the organic semiconductor layer is increased, the mobility is lowered, and the threshold value is shifted. There was a problem that would occur. In particular, in the third example, when the organic semiconductor layer is dry-etched using the resist pattern as a mask, the organic semiconductor layer is damaged by plasma and the above-described problem is likely to occur. Further, in the fourth example, it is difficult to control a portion that the destructive agent has on the organic semiconductor layer, and it is difficult to form a fine pattern with high accuracy.

  Accordingly, the present invention provides a method for forming an organic semiconductor pattern capable of forming a fine pattern without damaging the organic semiconductor layer, and further improves the characteristics of a semiconductor device using the organic semiconductor pattern. For the purpose.

  The method for forming an organic semiconductor pattern of the present invention for achieving such an object is characterized by being performed in the following procedure. First, a mask pattern is formed on the substrate. Next, an organic semiconductor layer is formed on the substrate on which the mask pattern is formed. Thereafter, the organic semiconductor layer portion on the mask pattern is selectively lifted off by peeling off the mask pattern from the substrate, and the organic semiconductor layer portion directly formed on the substrate at the opening of the mask pattern. Only leave as an organic semiconductor pattern.

  According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, wherein in the manufacture of a semiconductor device configured using an organic semiconductor pattern, an organic semiconductor pattern is formed by applying the above-described formation method.

  In such a formation method, since the mask pattern is peeled off from the substrate, only the organic semiconductor layer on the mask pattern is selectively selected without chemically affecting (damaging) the organic semiconductor layer. Lift-off can be removed. As a result, an organic semiconductor pattern composed of an organic semiconductor layer portion without deterioration and having maintained physical properties during film formation is formed on the substrate. Also, since the organic semiconductor pattern is formed by lift-off by peeling off the mask pattern formed directly above the substrate, it is advantageous for pattern miniaturization compared to the pattern formed on the metal mask from the organic semiconductor layer. is there.

  As described above, according to the present invention, it is possible to form a fine organic semiconductor pattern composed of an organic semiconductor layer portion having no deterioration while maintaining physical properties during film formation. As a result, in a semiconductor device using this organic semiconductor pattern, an increase in leakage current, a decrease in mobility, a shift in threshold value, and the like can be suppressed, and device characteristics can be improved.

  Hereinafter, embodiments in which the present invention is applied to the manufacture of a bottom gate / bottom contact type thin film transistor will be described with reference to the drawings.

  First, a substrate 1 is prepared as shown in FIG. The substrate 1 is made of a plastic substrate such as polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), or the like, or a buffer layer made of a resin material is provided on a plastic substrate or a glass substrate. It may be a substrate.

  Then, the gate electrode 3 is pattern-formed on the substrate 1 so as to cross each element region 1 a set on the substrate 1. Such pattern formation of the gate electrode 3 is performed by applying a printing method such as an ink jet method, a microcontact method, a screen printing method, or a photolithographic method.

  For example, in order to form the finer gate electrode 3 with high accuracy, it is preferable to perform pattern formation using a lithography method. In this case, pattern etching is performed using a resist pattern in which the formed electrode material layer is formed by lithography as a mask. Here, for example, the Au / Cr gate electrode 3 is formed to a thickness of 50 nm by etching an alloy layer of gold (Au) and chromium (Cr) using a resist pattern as a mask.

  In addition to the above, after forming the electrode material layer in a state covering the resist pattern formed by the lithography method, the upper electrode material layer portion is lifted off by removing the resist pattern to form the gate electrode 3. May be. In order to simplify the process, the electrode material layer is preferably formed by coating.

  In order to further simplify the process, it is preferable to form the gate electrode 3 by a printing method. In this case, the gate electrode 3 is formed by, for example, pattern-printing the coating system material by a printing method using a paste-like or liquid coating system material containing a conductive material and then solidifying it.

  Next, a gate insulating film 5 is formed on the substrate 1 on which the gate electrode 3 is patterned. Here, the gate insulating film 5 made of poly-4-vinylphenol is formed to a thickness of 500 nm by spin coating or slit coating.

  Next, a source / drain electrode 7 is formed in a pattern on the gate insulating film 5 at a position sandwiching the gate electrode 3. The pattern formation of the source / drain electrode 7 may be performed in the same manner as the gate electrode 3. Here, for example, the Au / Pt source / drain electrode 7 is formed to a thickness of 150 nm by etching a laminated film of gold (Au) and platinum (Pt) using a resist pattern as a mask.

  Up to the above, it is not necessary to be performed in a particularly limited process. For example, a technique similar to the conventional technique or another technique appropriately selected from other techniques may be applied, and the following process is a feature of the present invention. Process.

  First, as shown in FIG. 1B, a mask pattern 11 is formed on the substrate 1 on which the source / drain electrodes 7 are formed. The mask pattern 11 has an opening 11a that exposes the element region 1a.

  The mask pattern 11 destroys the structure of the base material layer while having a certain degree of adhesion to the base material layer (here, the gate insulating film 5 and the source / drain electrodes) covering the surface of the substrate 1. It shall be comprised with the material which can be peeled off without doing. Therefore, here, the adhesion between the gate electrode 5 and the mask pattern 11 and the adhesion between the source / drain electrode 7 and the mask pattern 11 are lower than the adhesion between the gate electrode 5 and the source / drain electrode 7. In addition, it is important to select the constituent material of the mask pattern 11. The source / drain electrode 7 is wired not only in the element region 1a but also in the outer region of the element region 1a.

  For example, when the gate insulating film 5 covering the substrate 1 is made of poly-4-vinylphenol and the source / drain electrode 7 on the gate insulating film 5 is made of an Au / Pt laminated film, the mask pattern 11 is formed. Polyvinyl alcohol is selected as an example of the material.

  As shown in the plan view of FIG. 2, the mask pattern 11 has a plurality of openings 11 a that expose each element region 1 a of the substrate 1 and a continuous shape above the substrate 1. It is preferable. This facilitates the work in the case where the mask pattern 11 is peeled off from the substrate 1 in the subsequent steps, and prevents the mask pattern 11 from being left behind. From this point of view, the planar shape of the mask pattern 11 may be divided into a plurality of pieces, but is preferably a shape in which no island-like portion is formed at the center on the substrate 1. However, as shown in FIG. 2, if the shape of the mask pattern 11 is one continuous shape on the substrate 1, the stripping operation is easiest. In addition, when the mask pattern 11 is peeled off, it is important that the film thickness is such that the mask pattern 11 does not break.

  Formation of the mask pattern 11 as described above is performed, for example, by applying a lithography method. In this case, a photosensitive resin is applied and formed above the substrate 1 on which the source / drain electrodes 7 are formed, and the mask pattern 11 having the above-described shape is formed by performing pattern exposure and development processing on the applied film. can get. Under the present circumstances, the mask pattern 11 which consists of polyvinyl alcohol is obtained by using photosensitive polyvinyl alcohol as photosensitive resin.

  Further, as other mask pattern forming methods, printing methods such as screen printing, gravure printing, flexographic printing, and ink jet printing may be applied. In this case, even if the resin is not photosensitive, the mask pattern 11 is obtained by forming a printed pattern having the above shape.

  As another mask pattern forming method, a dewetting method can be applied. When performing this method, first, a mask made of a water-repellent resist is formed in a portion to be an opening by some method (for example, lithography method). Next, a resin that is repelled by the water repellent resist portion is applied to the upper portion. As a result, the mask pattern 11 is formed in which the resin is applied in a self-aligning manner to other portions with the water-repellent resist portion as an opening. After the mask pattern 11 is formed, the water repellent resist may be removed by oxygen plasma treatment. Thereby, it is possible to form a fine mask pattern as compared with the printing method. If the pattern of the water repellent resist is formed by a method other than the lithography method, the mask pattern 11 can be formed by a resin having no photosensitivity.

  The mask pattern 11 may have a substantially vertical side wall, but more preferably has a reverse taper. The mask pattern 11 having the opening portion 11a having the side wall reverse taper shape is a resin that follows a change in the exposure amount in the depth direction of the photosensitive resin layer by lithography using, for example, a negative photosensitive resin. However, the present invention is not limited to this.

  Next, as shown in FIG. 1C, an organic semiconductor layer 13 is formed above the substrate 1 on which the mask pattern 11 is formed. The organic semiconductor layer 13 is formed by vapor deposition film formation or coating film formation such as an inkjet method, a dispense method, or a spin coating method. For example, when the organic semiconductor layer 13 made of pentacene is formed, the organic semiconductor layer 13 having a thickness of about 100 nm is formed by vapor deposition.

  The organic semiconductor layer 13 to be formed here is preferably thin enough to the thickness of the mask pattern 11 to such an extent that the organic semiconductor layer 13 is divided by the upper part of the mask pattern 11 and the inner part of the opening 11a. .

  Next, although not shown here, the step of weakening the adhesion between the mask pattern 11 and the underlying layer (here, the gate insulating film 5 and the source / drain electrode 7) by performing light irradiation as necessary. May be performed.

  After the above, the mask pattern 11 is peeled off from the substrate 1 as shown in FIG. In this case, as shown in the plan view of FIG. 3, first, the edge of the mask pattern 11 is turned up, and the mask pattern 11 is gradually peeled off the substrate 1 from the turned-up portion. The pattern 11 is physically removed.

  Thus, the organic semiconductor layer 13 formed on the mask pattern 11 is physically lifted off from the substrate 1 together with the mask pattern 11. On the other hand, the portion of the organic semiconductor layer 13 formed in the opening 11a of the mask pattern 11 remains on the substrate 1, and the remaining portion is patterned on the element region 1a of the substrate 1 as the organic semiconductor pattern 13a.

  When the mask pattern 11 is divided into a plurality of sheets, all or a necessary portion of the mask pattern 11 is peeled off from the substrate 1.

  As described above, on each element region 1a of the substrate 1, the gate electrode 3, the gate insulating film 5 covering the gate electrode 3, and the source / drain electrodes 7 provided at positions sandwiching the gate electrode 3 on the gate insulating film 5 are provided. A bottom gate / bottom contact type thin film transistor Tr composed of the organic semiconductor pattern 13a covering the source / drain electrode 7 is formed. Then, the semiconductor device 15 in which the thin film transistors Tr having such a configuration are arranged on the substrate 1 is obtained.

  According to the manufacturing method described above, the mask pattern 11 is peeled off from the substrate 1 as described with reference to FIGS. Without adding influence (damage), it is possible to selectively lift off the organic semiconductor layer 13 portion on the mask pattern 11. Thereby, it is possible to form on the substrate 1 an organic semiconductor pattern 13a composed of a portion of the organic semiconductor layer 13 that does not deteriorate while maintaining the physical properties during film formation.

  Further, since the organic semiconductor pattern 13a is formed by lift-off by peeling off the mask pattern 11 formed directly above the substrate 1, the pattern can be made finer than a pattern formed by film formation from a metal mask. It is advantageous, and it is possible to obtain an organic semiconductor pattern at a pitch finer than 10 μm. In particular, when the mask pattern 11 is formed by a lithography method, the organic semiconductor pattern 14a can be miniaturized to near the resolution limit in the lithography method. In the procedure of the above-described embodiment, it has been confirmed that the organic semiconductor pattern 13a can be formed with a 5 μm line and space, and the pattern width can be reduced to about 1 μm. Further, by forming the mask pattern 11 by a printing method, it is possible to improve the throughput in forming the organic semiconductor pattern 13a.

  As a result, in the semiconductor device (thin film transistor Tr) using the organic semiconductor pattern 13a, an increase in leakage current, a decrease in mobility, a shift in threshold value, and the like are suppressed, and element characteristics are improved. It becomes possible to improve the device performance of the configured semiconductor device.

  In the above-described embodiment, the configuration in which the present invention is applied to the manufacture of a semiconductor device including the bottom gate / bottom contact type thin film transistor Tr has been described. However, the present invention can be widely applied to a method for manufacturing a semiconductor device having an organic semiconductor pattern because the method for forming an organic semiconductor pattern is characteristic, and similar effects can be obtained.

  As such an example, for example, a semiconductor device provided with a plurality of thin film transistors other than bottom gate / bottom contact type, that is, bottom gate / top contact type, top gate / bottom contact type, and further top gate / top contact type thin film transistors It is also applicable to the manufacture of In addition to the thin film transistor, for example, the organic semiconductor pattern forming method described above may be applied to forming an organic semiconductor pattern such as an organic light emitting layer in an organic electroluminescent element. The present invention can also be applied to a method for manufacturing a semiconductor device as a display device in which the organic electroluminescent elements are arranged.

It is sectional process drawing explaining the manufacturing method of embodiment. It is a top view explaining the shape of a mask pattern. It is a top view which shows the process of peeling off a mask pattern.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 * Board | substrate, 11 ... Mask pattern, 11a ... Opening part, 13 ... Organic-semiconductor layer, 13a ... Organic-semiconductor pattern, 15 ... Semiconductor device

Claims (9)

Forming a mask pattern on the substrate;
Forming an organic semiconductor layer on the substrate on which the mask pattern is formed;
The organic semiconductor layer portion on the mask pattern is lifted off by peeling off the mask pattern from the substrate, and only the organic semiconductor layer portion directly formed on the substrate at the opening of the mask pattern is removed. And a step of leaving the organic semiconductor pattern as an organic semiconductor pattern. In the formation method of the organic-semiconductor pattern of Claim 1,
The method of forming an organic semiconductor pattern, wherein the mask pattern is formed by a lithography method using a photosensitive resin. In the formation method of the organic-semiconductor pattern of Claim 1,
The method of forming an organic semiconductor pattern, wherein the mask pattern is formed by a printing method. In the formation method of the organic-semiconductor pattern of Claim 1,
The method of forming an organic semiconductor pattern, wherein the mask pattern is formed by a dewetting method. In the formation method of the organic-semiconductor pattern of Claim 1,
A method for forming an organic semiconductor pattern, comprising: performing a step of weakening adhesion between the mask pattern and the substrate by irradiating the mask pattern with light before the mask pattern is peeled off from the substrate. In the formation method of the organic-semiconductor pattern of Claim 1,
The method for forming an organic semiconductor pattern, wherein the mask pattern has a side wall formed in an inversely tapered shape. In the formation method of the organic-semiconductor pattern of Claim 1,
The method for forming an organic semiconductor pattern, wherein the organic semiconductor layer is formed as a thin film than the mask pattern. In the method of forming an organic semiconductor pattern according to claim 1,
The method of forming an organic semiconductor pattern, wherein the mask pattern is formed as a continuous pattern on the substrate. A method of manufacturing a semiconductor device configured using an organic semiconductor pattern,
Forming a mask pattern on the substrate;
Forming an organic semiconductor layer on the substrate on which the mask pattern is formed;
The organic semiconductor layer portion on the mask pattern is lifted off by peeling off the mask pattern from the substrate, and only the organic semiconductor layer portion directly formed on the substrate at the opening of the mask pattern is removed. And a step of leaving the organic semiconductor pattern as an organic semiconductor pattern.

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