JPH06289431A - Formation of thin-film transistor and active matrix display element - Google Patents

Abstract

PURPOSE:To enable the simultaneous execution of beam annealing of an image display part and driving circuit part at the time of formation of TFTs by arranging the TFTs for pixel display and the TFTs for driving circuits in a straight form on the same substrate and to improve the through-put. CONSTITUTION:Amorphous silicon(a-Si) formed on the substrate is irradiated with an energy beam, such as eximer laser beam, from a beam annealing device of a scanning type and is thereby annealed to polysilicon. A first Si island group of the image display part consisting of H-shaped Si islands 1 which are the semiconductor channel parts of the thin-film transistors(TFTs) and a second Si island group of the driving circuit part consisting of Si islands 2A, 2B, C... are thereafter formed by photolithography and etching. Scanning is executed at the scanning pitch of the row pitch a of pixels in the case of execution of the scanning with the laser beam in a row direction. The second Si island group of the driving circuit part on the gate side is previously so arranged and designed as to be formed on the extension line in the row direction of the first Si island group of the pixel display part at this time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrangement structure of thin film transistors (TFTs) in an active matrix display device and a method of forming the TFTs.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for a flat panel display which replaces a CRT, and among them, a liquid crystal display element (LCD) is regarded as the most promising. In recent years, active matrix type LCDs using TFTs have been actively developed in response to the demands for colorization and high speed.

Amorphous silicon (a-Si) is generally used as a semiconductor layer in a TFT, but by using polysilicon (poly-Si) instead of the amorphous silicon (a-Si), a driving circuit that requires high-speed operation can be provided in a pixel. It is possible to form them on the same substrate.

When an ordinary glass substrate is used, as one means for obtaining poly-Si in a low temperature process, beam annealing is performed using laser light to polycrystallize a-Si (poly-Si). There is a way. In the beam annealing, manufacturing throughput can be improved by using a method of irradiating only a necessary portion with laser light or the like and not forming polycrystal of Si in a portion where a TFT is not formed.

When only a pixel display transistor is formed on a substrate by using a scanning type beam annealing device, laser light is scanned and irradiated by the number of rows (or columns) of a matrix forming pixels. do it. However, when the drive circuit is formed on the same substrate, the drive circuit configured outside the display screen has its own layout configuration in that part, and the relationship with the beam annealing is not taken into consideration. As a result, the number of scans for irradiating the drive circuit unit with the beam has increased. As a result, the throughput is lowered.

[0006]

When a poly-Si-TFT active matrix substrate for an active matrix LCD is manufactured by using a scanning type laser annealing device, a driving system which is a circuit system different from the pixel display section is used. If the circuit portion is similarly formed by beam annealing, the number of times of beam irradiation scanning is increased, resulting in a decrease in throughput. The object of the present invention is to eliminate such drawbacks.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and provides an active matrix display device in which a pixel display TFT and a drive circuit TFT are formed on the same substrate. Provided is an active matrix display element (1) characterized in that a pixel display TFT and a drive circuit TFT are arranged linearly.

Further, there is provided an active matrix display element (2) characterized in that, in the above active matrix display element (1), a linear arrangement is arranged in a row direction of pixels.

Further, there is provided an active matrix display element (3) characterized in that, in the above active matrix display element (1), a linear arrangement is arranged in a pixel column direction.

A method of forming a TFT in which α-Si is converted into poly-Si by beam annealing, which comprises a first α-Si island group used as a thin film transistor for pixel display,
It is planned that the second α-Si islands, which will be TFTs for the drive circuit, be arranged linearly in advance in the row direction or the column direction of the matrix on the same substrate, and then these first α-Si islands will be arranged. -Si island group and the second α-Si island group on the predetermined positions, along the row direction or the column direction of the matrix, each one row or each column by one linear beam irradiation. Provided is a method for forming a TFT, which comprises irradiating a beam, annealing α-Si, converting it into poly-Si, and forming a Si island through a photolithography process.

The active elements such as thin film transistors for pixel display are originally arranged linearly in the row and column directions of the substrate. In accordance with this, the active elements for the drive circuit, specifically, the active layers (semiconductor channel portions) such as TFTs, which are located in the peripheral portion on the outer side, further extend in a linear array of the active elements in the image display portion. Layout design.

FIG. 5 shows the overall arrangement on the substrate.
Arrows in FIG. 5 indicate the column direction of the substrates. In FIG.
The portion indicated by the diagonal line in the center is the pixel display portion 8. In addition, the four driving circuits 7a, 7b, 7c, 7 are provided around the four grids.
d is provided. In FIG. 5, the arrangement configuration of Si islands in a region α surrounded by a thick solid line and a region β surrounded by a broken line is shown in FIG.
4A to 4C, further detailed description will be given in each of the following embodiments. Note that the arrows in each drawing point in the same direction (leftward in the drawings).

[0013]

【Example】

(Embodiment 1) FIG. 1 shows Embodiment 1. The a-Si film formed on the substrate is irradiated with an energy beam such as an excimer laser beam, an electron beam, or a continuous wave argon ion laser using a scanning type beam annealing device, and annealed to form poly-Si. After that, by photolithography and etching, the first Si island group of the image display unit formed of the H-shaped Si islands 1 to be the semiconductor channel portion of the TFT, and Si
The second Si of the drive circuit section including the islands 2A, 2B, 2C, ...
Form an island group.

Laser beam scanning is performed in the row direction (gate, bus,
When performed in parallel with the line), the scanning pitch is the row pitch a of the pixels. At this time, a second Si island group (H-shaped portion in the figure left by etching Si) of the drive circuit section on the gate side is formed on the extension line in the row direction of the first Si island group of the pixel display section. The layout is designed beforehand.

Thereafter, beam irradiation is performed to polycrystallize α-Si. The irradiated beam spot locus 10 is shown superimposed on the Si islands to be formed thereafter. In the first embodiment, all Si islands are included in the beam spot trajectory 10 irradiated. However, the entire Si island does not necessarily need to be poly-Si, and only the region that should be the semiconductor channel portion of the TFT may be poly-Si. for that reason,
The orientation of the Si island may be arbitrary.

In the peripheral portion, a CMO is used as a driving element.
When S is used, it can be obtained by simultaneously polycrystallizing the respective semiconductor channel portions. Reference numeral 2 shown in FIG.
Each set of A, 2B, and 2C can be a semiconductor channel portion of a pair of CMOS. The same can be applied to the following embodiments.

(Second Embodiment) FIG. 2 shows a second embodiment. Such an arrangement configuration is also possible in the peripheral portion. The directions of the Si islands 1 forming the first Si island group and the Si islands 2A, 2B, 2C forming the second Si island group are located in an orthogonal relationship. The Si islands 2A, 2B, and 2C are polycrystallized by intersecting the beam spot locus 10 with which at least the respective semiconductor channel portions are irradiated.

(Embodiment 3) Similarly, since it is not necessary for the Si islands to be completely aligned in a straight line, a structure like Embodiment 3 shown in FIG. 3 may be used. The Si islands 2A, 2B, and 2C that form the second Si island group are arranged in parallel at their respective positions. All H-shaped Si islands have beam spot locus 10
Is covered with.

(Embodiment 4) When beam scanning is performed in the column direction (parallel to the source bus lines), the scanning pitch is the column pitch b of pixels. In this case, as shown in FIG. 4, the second Si island group (Si island 2A,
2B, 2C) are formed on the extension lines in the column direction of the first Si island group (Si island 1) of the pixel display portion. The beam spot trajectory 11 scanned in the column direction is
i island is covered.

[0020]

According to the present invention, since the TFT for the driving circuit and the TFT for displaying the pixel are arranged linearly, the TFT
The beam annealing at the time of formation of the TFTs enables the poly-Si formation of the TFTs of both the drive circuit and the pixel display circuit almost simultaneously. Therefore, it is not necessary to separately perform beam annealing for the drive circuit, which greatly improves the throughput and reduces the required time to half or less.

Further, since the semiconductor channel portion is not formed separately but by scanning the beam irradiation in the row direction or the column direction of the matrix in a short time, the characteristic variation of each TFT is reduced, and the final product is manufactured. Has improved the electrical characteristics.

A similar effect such as improvement in manufacturing efficiency is expected in a method of performing beam scanning to perform some processing on a transistor, such as a scanning type beam annealing apparatus.

The present invention can be applied to various circuit formations as long as the effect is not lost.

[Brief description of drawings]

FIG. 1 is a partially enlarged plan view showing an arrangement of Si islands in a first embodiment.

FIG. 2 is a partially enlarged plan view showing an arrangement of Si islands in a second embodiment.

FIG. 3 is a partially enlarged plan view showing an arrangement of Si islands in a third embodiment.

FIG. 4 is a partially enlarged plan view showing the arrangement (column direction) of Si islands in the fourth embodiment.

FIG. 5 is a plan view schematically showing an active matrix substrate for LCD.

[Explanation of symbols]

 1, 2A, 2B, 2C: Si island 10, 11: Beam spot locus

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01L 21/336

Claims (4)

[Claims] 1. In an active matrix display device in which a thin film transistor for pixel display and a thin film transistor for drive circuit are formed on the same substrate, the thin film transistor for pixel display and the thin film transistor for drive circuit are linearly arranged. An active matrix display device characterized by the above. 2. The active matrix display element according to claim 1, wherein the linear arrangement is arranged in the row direction of the pixels. 3. The active matrix display element according to claim 1, wherein a linear arrangement is arranged in a pixel column direction. 4. Poly-α-Si is formed by beam annealing.
A method of forming a thin film transistor for converting to Si, comprising a first α-Si used as a thin film transistor for pixel display.
It is planned that the island group and the second α-Si island group used as the thin film transistor for the driving circuit are arranged in advance linearly along the row direction or the column direction of the matrix on the same substrate, and then these First α-Si island group and second α-S
Beam each row or each column by a single linear beam irradiation on the predetermined positions of both of the i island groups along the row direction or the column direction of the matrix,
A method for forming a thin film transistor, which comprises annealing α-Si to form poly-Si, and further forming a Si island through a photolithography process.