KR20080023472A - Manufacturing method of thin-film transistors - Google Patents

Abstract

A method for manufacturing a thin film transistor is provided to perform precise control of overlap and channel width between a gate electrode and a source/drain electrode by controlling exposure time and light intensity of a photo resist. A method for manufacturing a thin film transistor comprises the steps of: forming a gate electrode(102) on a transparent substrate(101); forming a transparent source/drain electrode(104); coating a negative photo resist(105) over the source/drain electrode; exposing the substrate until the negative photo resist is overlapped with the gate electrode from the opposite side of deposition and developing it; etching a channel of the source/drain electrode; removing the photo resist; and forming a semiconductor layer.

Description

Manufacturing method of thin-film transistors

1A to 1D show a method of manufacturing a thin film transistor according to the present invention.

2A to 2D illustrate a method of manufacturing a thin film transistor according to the present invention, and a method of forming a semiconductor layer subsequent to FIGS. 1A to 1D.

※ Description of main part of drawing ※

101: transparent substrate 102: gate electrode

103: gate insulating layer 104: source / drain electrode

105: photoresist 106: semiconductor layer

The present invention relates to a method for manufacturing a thin film transistor.

More specifically, the present invention uses an optically transmissive gate insulating film and a source / drain electrode to expose the opposite side of the substrate, and exposes the overlap of the gate electrode and the source / drain electrode to the entire substrate by overexposing the negative photoresist. It relates to a thin film transistor manufacturing method which can be formed uniformly over.

As the information age progresses, elements for mass information processing and display elements for displaying the same are being rapidly developed. Display devices are rapidly changing from conventional CRTs to flat panel display devices such as OLED (organic light emitting diode) and plasma display panel (PDP).

Among them, OLED is becoming more important as next generation display with advantages such as self-luminous and low power. Such OLEDs require transistors for each pixel in an active spherical method having high resolution and low power. When the transistors are fabricated using organic materials, OLEDs have more advantages due to their low cost and flexibility.

Among these organic transistors, pentacene, which is an organic material, exhibits performance similar to that of a silicon transistor, which is an existing semiconductor material. Device structures using organic semiconductors such as pentacene are classified into two types: top contact structure (the electrode is formed on the pentacene) and bottom contact structure (the electrode is formed first and the pentacene is formed thereon) according to the contact method between the electrode and the organic semiconductor. Can be divided into:

Comparing the advantages and disadvantages of each structure, the top contact structure has superior device characteristics than the bottom contact structure, and the vacuum chamber is formed through the shadow mask electrode in order not to degrade the performance of the organic material formed. There is a problem in that there is a problem in the integration because it must be produced in-house.

In the case of the bottom contact structure, the device characteristics are lower than that of the top contact structure, but since the integration is possible in the process, the actual display can be applied.

In the case of the thin film transistor using the organic semiconductor as described above, the channel width of the organic semiconductor layer is irregularly formed, so that there is a problem in that the performance of the entire substrate is not constant.

There is a need for a method capable of solving the problems of various thin film transistors, particularly organic semiconductor thin film transistors using organic semiconductors.

An object of the present invention is to provide a method in which overlap between a gate electrode and a source / drain electrode and a channel width can be uniformly formed over a thin film transistor substrate.

It is also an object of the present invention to provide a method capable of very precisely controlling the overlap between the gate electrode and the source / drain electrode and the channel width.

According to one or more exemplary embodiments, a method of manufacturing a thin film transistor includes: forming a gate electrode on a transparent substrate; Forming a transparent source / drain electrode; Applying a negative photoresist over said source / drain electrodes; Exposing and developing the substrate on opposite sides of the stacking direction; Etching the channel portion of the source / drain electrode; Removing the photoresist; And forming a semiconductor layer.

Hereinafter, the manufacturing method of the present invention will be described in detail with reference to the accompanying drawings.

1A to 1D show a method of manufacturing a thin film transistor according to the present invention.

As shown in Fig. 1A, a gate electrode 102 is formed on a transparent substrate 101 such as glass or plastic. As the gate electrode 102, various materials may be used according to embodiments, such as a metal layer in which Al / Nd is sequentially stacked and an alloy of Cr / Mo.

As shown in FIG. 1B, a gate insulating layer 103 is stacked on the substrate 101 to cover the gate electrode 102, and a source / drain electrode 104 is stacked thereon.

The gate insulating layer 103 must be a light transmissive material because ultraviolet rays for photoresist exposure can pass therethrough, and inorganic materials such as SiO 2 and SiNx can be used, and organic insulating films such as polyvinyl phenol (PVP) and pyriline can also be used. Can be.

Likewise, in the manufacturing method according to the present invention, the source / drain electrode 104 should also be a light transmissive metal through which light can pass. As the source / drain electrode 104, a transparent metal such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc tin oxide (ZTO), or poly 3,4-ethylenedioxythiophene (PDOT) may be used.

Then, in FIG. 1C, the remaining portions except for the channel portion (center portion) of the source / drain electrode 104 are patterned. It can be etched by etching using a photolithography method. In the method of the present invention, the patterning of the channel portions of the source / drain electrodes 104 is performed more accurately through a separate patterning process.

As shown in Fig. 1D, a negative photoresist 105 is applied to the entire surface of the substrate, and the photoresist 105 is exposed by irradiating ultraviolet rays on the opposite side of the substrate stacking direction, that is, under the substrate. At this time, the gate electrode 102 serves as a mask.

Since the photoresist 105 is a negative type, the exposed portion remains, and the portion covered by the gate electrode 102 is removed by development.

At the time of exposure, exposure time is lengthened or light intensity is strengthened so that the part covered by the gate electrode 102 may also be exposed. That is, the peripheral portions of the gate electrode 102 serving as a mask are also exposed by a predetermined width. The portion exposed to the inner side of the gate electrode 102 forms an overlap of the gate electrode 102 and the source / drain electrode 104.

In order to secure the electro-optic characteristics of the thin film transistor substrate, an overlap of a predetermined width is required between the gate electrode 102 and the source / drain electrodes.

Since the exposure degree is proportional to both the exposure time and the light intensity, in some embodiments, the exposure time is the same as before, and the intensity of the light is strengthened, thereby overlapping the overlap between the gate electrode 102 and the source / drain electrode 104. It may be formed.

In addition, since the exposure must be performed while passing through the gate insulating layer 103 and the source / drain electrodes 104 on the opposite side of the substrate, it is preferable to make the intensity of light much stronger than that of a conventional conventional exposure process.

2A to 2D illustrate a method of manufacturing a thin film transistor according to the present invention, and show a method of forming a channel layer, that is, a semiconductor layer, continued from FIGS. 1A to 1D.

As shown in FIG. 2A, an unexposed portion of the negative photoresist 105 is developed to form a photoresist 105 pattern.

Then, as shown in FIG. 2B, the source / drain electrode 104 is patterned to form a channel portion in which a semiconductor layer is to be formed in the center of the source / drain electrode 104.

Using the gate electrode 102 as a mask, the exposure time or the intensity of the light was adjusted at the time of exposure on the opposite side of the substrate to partially cover the portion covered with the gate electrode 102, so that the source / drain electrode 104 and the gate electrode ( An area overlapping each other, that is, an overlap, is formed between the 102.

In the manufacturing method of the thin film transistor according to the present invention, the overlap between the gate electrode 102 and the source / drain electrode 104 can be uniformly and precisely controlled over the entire substrate by adjusting the exposure time or the intensity of light during exposure.

Then, as shown in Fig. 2C, the photoresist 105 is removed. It can be removed using a suitable stripper liquid suitable for the photoresist 105.

As shown in FIG. 2D, the semiconductor layer 106 is formed in the center of the channel portion, that is, the source / drain electrode 105. Organic materials, such as pentacene, may be used, and inorganic materials, such as a-Si and poly Si, may be used.

In the case of using a recently developed soluable pentacene or liquid organic material as the semiconductor layer 106, the semiconductor layer 106 is formed in a channel portion formed at the center of the source / drain electrode 104 through an inkjet process. Can be formed more stably.

As described above, in the thin film transistor manufacturing method according to the present invention, the overlap between the gate electrode 102 and the source / drain electrode 104 is controlled by adjusting the exposure time and the light intensity of the photoresist 105.

According to the method of manufacturing the thin film transistor of the present invention, the overlap between the gate electrode and the source / drain electrode and the channel width can be uniformly formed over the thin film transistor substrate.

Claims (4)

Forming a gate electrode on the transparent substrate; Forming a transparent source / drain electrode; Applying a negative photoresist over said source / drain electrodes; Exposing and developing the substrate on opposite sides of the stacking direction; Etching the channel portion of the source / drain electrode; Removing the photoresist; And Forming a semiconductor layer; Thin film transistor manufacturing method comprising a. The method of claim 1, Exposing and developing the substrate on the opposite side of the stacking direction, And exposing the negative photoresist to a portion overlapping with the gate electrode. The method of claim 1, The source / drain electrode may be any one of ITO, IZO, ZTO, and PDOT. The method of claim 1, Forming the semiconductor layer, The semiconductor layer is a liquid organic semiconductor, Forming the semiconductor layer by an inkjet process.

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