TWI659554B - Organic thin film transistor - Google Patents

Abstract

An organic thin film transistor includes a substrate, a source / drain layer, a first buffer layer, a semiconductor layer, a gate insulating layer, and a gate. The source / drain layer is on the substrate. The source / drain layer has a source region and a drain region. The first buffer layer is located between the source region and the drain region, and the first buffer layer covers at least part of the source region and at least part of the drain region. The semiconductor layer is located on the source / drain layer and the first buffer layer. The first buffer layer is located between the semiconductor layer, the source region, the drain region, and the substrate. The gate insulating layer covers the source / drain layer and the semiconductor layer. The gate is located on the gate insulation layer, and a part of the gate insulation layer is located between the gate and the semiconductor layer.

Description

   Organic thin film transistor   

This case relates to an organic thin film transistor.

Generally speaking, the material of the source / drain layer of an organic thin film transistor is gold, silver, or other metal capable of reacting with a self-assembly monolayer (SAM). The self-assembly monolayer is organic. Semiconductor layer of a thin film transistor.

When fabricating an organic thin film transistor, the source / drain layer is first patterned to form a source and drain region with an interval, and then a semiconductor layer is coated on the source and drain regions near the pitch and the source. The distance between the pole and drain regions. However, due to the material of the source / drain layer, after patterning the source / drain layer, a tapered undercut structure is generated at a position close to the distance between the source region and the drain region. In this way, the semiconductor layer in the pitch will have a larger thickness near the wedge-shaped undercut structure, and the semiconductor layer with a larger thickness will affect the molecular arrangement. In other words, the uneven thickness of the semiconductor layer will adversely affect the electrical stability of the organic thin film transistor.

One aspect of the present invention is an organic thin film transistor.

According to an embodiment of the present invention, an organic thin film transistor includes a substrate, a source / drain layer, a first buffer layer, a semiconductor layer, a gate insulating layer, and a gate. The source / drain layer is on the substrate. The source / drain layer has a source region and a drain region. The first buffer layer is located between the source region and the drain region, and the first buffer layer covers at least part of the source region and at least part of the drain region. The semiconductor layer is located on the source / drain layer and the first buffer layer. The first buffer layer is located between the semiconductor layer, the source region, the drain region, and the substrate. The gate insulating layer covers the source / drain layer and the semiconductor layer. The gate is located on the gate insulation layer, and a part of the gate insulation layer is located between the gate and the semiconductor layer.

In one embodiment of the present invention, the organic thin film transistor further includes a protective layer. A protective layer is provided along the semiconductor layer. The semiconductor layer is located between the protection layer and the source / drain layer, and between the protection layer and the first buffer layer.

In one embodiment of the present invention, the organic thin film transistor further includes a photoresist layer. The photoresist layer is located on the protection layer, and is located between the gate insulation layer and the protection layer.

In one embodiment of the present invention, the organic thin film transistor further includes a barrier layer. The barrier layer is on the substrate. The first buffer layer is located between the semiconductor layer, the source region, the drain region, and the barrier layer.

In one embodiment of the present invention, the organic thin film transistor further includes a second buffer layer. The second buffer layer is on the barrier layer. The first buffer layer is located between the semiconductor layer, the source region, the drain region, and the second buffer layer.

In an embodiment of the present invention, the source region has a first surface and a second surface opposite to each other, and has a sidewall adjacent to the first surface and the second surface, the first surface faces the substrate, and the sidewall and the first surface are at an obtuse angle .

In an embodiment of the present invention, the first buffer layer has a central portion and an extension portion, the central portion is located between the source region and the drain region, and the extension portion is located on the second surface of the source region.

In an embodiment of the present invention, the at least part of the source region is located between the extending portion and the central portion.

In an embodiment of the present invention, the first buffer layer is in contact with a sidewall of the source region.

In an embodiment of the present invention, the drain region has a first surface and a second surface opposite to each other, and has a sidewall adjacent to the first surface and the second surface, the first surface faces the substrate, and the sidewall and the first surface are at an obtuse angle. .

In the above embodiment of the present invention, since the first buffer layer is located between the source region and the drain region and covers at least part of the source region and at least part of the drain region, the semiconductor layer may be located at the source / drain layer With the first buffer layer. In this design, the first buffer layer can be used to fill the space between the source region and the drain region, so as to prevent the semiconductor layer from being formed on the tapered undercut structure of the source region and the drain region to produce a larger thickness. In this way, the semiconductor layer can have a uniform thickness without affecting the molecular arrangement, and can improve the electrical stability of the organic thin film transistor.

100, 100a, 100b, 100c, 100d‧‧‧ organic thin film transistor

110‧‧‧ substrate

120‧‧‧Source / Drain Layer

122‧‧‧Source area

124‧‧‧ Drain

125a‧‧‧first surface

125b‧‧‧Second surface

126‧‧‧ sidewall

127a‧‧‧first surface

127b‧‧‧Second surface

128‧‧‧ sidewall

130‧‧‧first buffer layer

132‧‧‧ Central

134, 136‧‧‧ extension

140‧‧‧Semiconductor layer

150‧‧‧Gate insulation

160‧‧‧Gate

170‧‧‧ protective layer

180‧‧‧Photoresistive layer

190‧‧‧ barrier layer

210‧‧‧ passivation layer

220‧‧‧pixel electrode

230‧‧‧Second buffer layer

θ1, θ2‧‧‧ obtuse angle

FIG. 1 is a cross-sectional view of an organic thin film transistor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an organic thin film transistor according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of an organic thin film transistor according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view of an organic thin film transistor according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view of an organic thin film transistor according to an embodiment of the present invention.

In the following, a plurality of embodiments of the present invention will be disclosed graphically. For the sake of clarity, many practical details will be described in the following description. It should be understood, however, that these practical details should not be used to limit the invention. That is, in some embodiments of the present invention, these practical details are unnecessary. In addition, in order to simplify the drawings, some conventional structures and components will be shown in the drawings in a simple and schematic manner.

FIG. 1 is a cross-sectional view of an organic thin film transistor 100 according to an embodiment of the present invention. As shown, the organic thin film transistor 100 includes a substrate 110, a source / drain layer 120, a first buffer layer 130, a semiconductor layer 140, a gate insulating layer 150, and a gate 160. The source / drain layer 120 is located on the surface of the substrate 110. The source / drain layer 120 has a source region 122 and a drain region 124, and the source region 122 and the drain region 124 are separated by a distance. The first buffer layer 130 fills this gap, that is, it is located between the source region 122 and the drain region 124. In addition, the first buffer layer 130 extends to the source region 122 and the drain region 124 to cover at least a portion of the source region 122 and at least a portion of the drain region 124. The material of the first buffer layer 130 may be a polymer.

The semiconductor layer 140 is located on the source / drain layer 120 and the first buffer layer 130, so that the first buffer layer 130 is located between the semiconductor layer 140, the source region 122, the drain region 124 and the substrate 110. That is, the first buffer layer 130 is surrounded by the semiconductor layer 140, the source region 122, the drain region 124 and the substrate 110. The gate insulating layer 150 covers the source / drain layer 120 and the semiconductor layer 140. The gate 160 is located on the gate insulating layer 150, and a part of the gate insulating layer 150 is located between the gate 160 and the semiconductor layer 140.

In this embodiment, the material of the source / drain layer 120 may be silver or gold. When the source / drain layer 120 is patterned (eg, an etching process), a tapered undercut structure is generated in the source region 122 and the drain region 124, and obtuse angles θ1 and θ2 are generated. In addition, the material of the gate insulating layer 150 may include an organic material to become an organic gate insulator (Organic Gate Insulator; OGI).

The semiconductor layer 140 may be formed by spin coating or slit coating, but it is not intended to limit the present invention. Since the first buffer layer 130 is located between the source region 122 and the drain region 124 and covers at least a portion of the source region 122 and at least a portion of the drain region 124, the semiconductor layer 140 may be located at the source / drain layer 120 and On the first buffer layer 130. With this design, the first buffer layer 130 can be used to fill the space between the source region 122 and the drain region 124 to avoid the semiconductor layer 140 being formed in the wedge-shaped undercut structure region of the source region 122 and the drain region 124. The larger thickness results in uneven thickness of the entire semiconductor layer 140, which further affects the electrical stability. The first buffer layer 130 is located below the semiconductor layer 140, so that the semiconductor layer 140 can have a uniform thickness when it is formed to improve the electrical stability of the organic thin film transistor 100.

In this embodiment, the source region 122 has a first surface 125 a and a second surface 125 b opposite to each other, and has a sidewall 126 adjacent to the first surface 125 a and the second surface 125 b. The drain region 124 has a first surface 127a and a second surface 127b opposite to each other, and has a sidewall 128 adjacent to the first surface 127a and the second surface 127b. The first surface 125a of the source region 122 and the first surface 127a of the drain region 124 both face the substrate 110, and the second surface 125b of the source region 122 and the second surface 127b of the drain region 124 both face away from the substrate 110. The sidewall 126 of the source region 122 is at an obtuse angle θ1 with the first surface 125a, and the sidewall 128 of the drain region 124 is at an obtuse angle θ2 with the first surface 127a.

In addition, the first buffer layer 130 has a central portion 132 and extension portions 134 and 136. The central portion 132 is located between the source region 122 and the drain region 124. The extension portion 134 is located on the second surface 125 b of the source region 122, and the extension portion 136 is located on the second surface 127 b of the drain region 124. In addition, the first buffer layer 130 contacts the sidewall 126 and the second surface 125b of the source region 122, and the first buffer layer 130 contacts the sidewall 128 and the second surface 127b of the drain region 124. As such, at least a portion of the source region 122 is located between the extension 134 and the central portion 132, and at least a portion of the drain region 124 is located between the extension 136 and the central portion 132. Such a design can ensure that the semiconductor layer 140 near the sidewalls 126 and 128 (wedge-shaped undercut structure) can be separated and supported by the first buffer layer 130 to prevent the semiconductor layer 140 from falling between the source region 122 and the drain region 124. In the space, the thickness of the semiconductor layer 140 is not uniform.

It should be understood that the connection relationships, materials and functions of components that have already been described will not be repeated here, but they will be described together. In the following description, other types of organic thin film transistors will be described.

FIG. 2 is a cross-sectional view of an organic thin film transistor 100a according to an embodiment of the present invention. The organic thin film transistor 100a includes a substrate 110, a source / drain layer 120, a first buffer layer 130, a semiconductor layer 140, a gate insulating layer 150, and a gate 160. The difference from the embodiment in FIG. 1 is that the organic thin film transistor 100a further includes a protective layer 170, a photoresist layer 180, and a barrier layer 190. The protection layer 170 is disposed along the surface of the semiconductor layer 140, the semiconductor layer 140 is located between the protection layer 170 and the source / drain layer 120, and the semiconductor layer 140 is also located between the protection layer 170 and the first buffer layer 130.

In addition, the photoresist layer 180 is located on the protective layer 170 and is located between the gate insulating layer 150 and the protective layer 170. The barrier layer 190 is located on the substrate 110 and is disposed along the surface of the substrate 110. Therefore, the first buffer layer 130 of the organic thin film transistor 100a is located between the semiconductor layer 140, the source region 122, the drain region 124, and the barrier layer 190 . That is, the first buffer layer 130 is surrounded by the semiconductor layer 140, the source region 122, the drain region 124 and the barrier layer 190.

In this embodiment, the material of the protective layer 170 may include an organic material, and becomes an organic protective layer (Organic Protective Layer (OPL)). The material of the photoresist layer 180 may include an organic material, and becomes an organic photoresist (Organic Photoresist; OPR) layer. The material of the barrier layer 190 may include silicon nitride (SiNx) or silicon oxide (SiOx), but it is not intended to limit the present invention.

FIG. 3 is a cross-sectional view of an organic thin film transistor 100b according to an embodiment of the present invention. The organic thin film transistor 100b includes a substrate 110, a source / drain layer 120, a first buffer layer 130, a semiconductor layer 140, a gate insulating layer 150 and a gate 160, a protective layer 170, a photoresist layer 180, and a barrier layer 190. . The difference from the embodiment in FIG. 2 is that the organic thin film transistor 100b further includes a passivation layer 210 and a pixel electrode 220. The passivation layer 210 covers the gate electrode 160 and the gate insulation layer 150, and the pixel electrode 220 is located on the passivation layer 210. In this embodiment, a material of the passivation layer 210 may include an organic material, and becomes an organic passivation (OPV) layer.

FIG. 4 is a cross-sectional view of an organic thin film transistor 100c according to an embodiment of the present invention. The organic thin film transistor 100c includes a substrate 110, a source / drain layer 120, a first buffer layer 130, a semiconductor layer 140, a gate insulating layer 150, a gate 160, a protective layer 170, a photoresist layer 180, and a barrier layer 190. . The difference from the embodiment in FIG. 2 is that the organic thin film transistor 100c further includes a second buffer layer 230. The second buffer layer 230 is located on the barrier layer 190 such that the first buffer layer 130 is located between the semiconductor layer 140, the source region 122, the drain region 124 and the second buffer layer 230. That is, the first buffer layer 130 is surrounded by the semiconductor layer 140, the source region 122, the drain region 124 and the second buffer layer 230.

FIG. 5 is a cross-sectional view of an organic thin film transistor 100d according to an embodiment of the present invention. The organic thin film transistor 100d includes a substrate 110, a source / drain layer 120, a first buffer layer 130, a semiconductor layer 140, a gate insulating layer 150, a gate 160, a protective layer 170, a photoresist layer 180, and a barrier layer 190. And the second buffer layer 230. The difference from the embodiment in FIG. 4 is that the organic thin film transistor 100d further includes a passivation layer 210 and a pixel electrode 220. The passivation layer 210 covers the gate electrode 160 and the gate insulation layer 150, and the pixel electrode 220 is located on the passivation layer 210.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and retouches without departing from the spirit and scope of the present invention. The scope shall be determined by the scope of the attached patent application.

Claims (10)

An organic thin film transistor includes: a substrate; a source / drain layer on the substrate; the source / drain layer has a source region and a drain region; a first buffer layer is disposed on the substrate; Between the source region and the drain region, and covering at least a portion of the source region and at least a portion of the drain region; a semiconductor layer on the source / drain layer and the first buffer layer, and The semiconductor layer has a substantially uniform thickness, wherein the first buffer layer is located between the semiconductor layer, the source region, the drain region and the substrate; a gate insulating layer covering the source / drain layer and The semiconductor layer; and a gate electrode located on the gate insulation layer, and a part of the gate insulation layer is located between the gate electrode and the semiconductor layer. The organic thin film transistor according to claim 1, further comprising: a protective layer disposed along the semiconductor layer, wherein the semiconductor layer is located between the protective layer and the source / drain layer, and the protective layer and the Between the first buffer layers. The organic thin film transistor according to claim 2, further comprising: a photoresist layer on the protective layer and between the gate insulating layer and the protective layer. The organic thin film transistor according to claim 1, further comprising: a barrier layer on the substrate, wherein the first buffer layer is located on the semiconductor layer, the source region, the drain region, and the barrier layer. between. The organic thin film transistor according to claim 4, further comprising: a second buffer layer located on the barrier layer, wherein the first buffer layer is located on the semiconductor layer, the source region, the drain region, and Between the second buffer layers. The organic thin film transistor according to claim 1, wherein the source region has a first surface and a second surface opposite to each other, and has a sidewall adjacent to the first surface and the second surface, the first surface It faces the substrate, and the side wall is at an obtuse angle with the first surface. The organic thin film transistor according to claim 6, wherein the first buffer layer has a central portion and an extension portion, the central portion is located between the source region and the drain region, and the extension portion is located on the source electrode Area on the second surface. The organic thin film transistor according to claim 7, wherein at least part of the source region is located between the extension portion and the central portion. The organic thin film transistor according to claim 6, wherein the first buffer layer contacts the sidewall of the source region. The organic thin film transistor according to claim 1, wherein the drain region has a first surface and a second surface opposite to each other, and a sidewall adjacent to the first surface and the second surface, the first surface It faces the substrate, and the side wall is at an obtuse angle with the first surface.