CN1322563C - Laser annealing device for preparing polysilicon film layer and method for forming polysilicon film layer - Google Patents

Abstract

The invention provides a laser annealing device for preparing a polycrystalline silicon film layer, which can prevent an amorphous silicon layer at the edge area of a substrate from being damaged during laser annealing. The invention provides a laser annealing device, which comprises a shielding structure, wherein when the amorphous silicon film is subjected to laser annealing to form a polycrystalline silicon film, the shielding structure can resist laser in the edge area of a substrate so as to prevent the laser from completely irradiating the amorphous silicon film in the edge area of the substrate.

Description

Laser annealing device for preparing polysilicon film layer and method for forming polysilicon film layer

technical field

The present invention relates to a laser annealing device for preparing a polysilicon film, and in particular to a low temperature polysilicon process (low temperature polysilicon process) using a sequential lateral solidification (SLS) method; LTPS process) used in the laser annealing device.

Background technique

Thin film transistors are active elements commonly used in active matrix type flat panel displays, and are usually used to drive active matrix type liquid crystal displays, active matrix type organic light-emitting displays (active matrix type organic light-emitting display) and other devices. Semiconductor silicon films in thin film transistors can generally be classified into polysilicon (poly-silicon) films and amorphous silicon (a-Si:H) films.

Although amorphous silicon thin film has the advantages of low process temperature, suitable for mass production because it can be prepared by vapor deposition method, mature process technology and high yield rate, etc., due to the good electrical conductivity of polysilicon, thin film transistors using polysilicon film have relatively high performance. High field effect mobility enables transistors to be used in circuits with high operating speeds, and the integration of drive circuits is better. Coupled with the development of low-temperature polysilicon processes, it has gradually replaced amorphous silicon films.

There are roughly three common manufacturing methods for polysilicon thin films. The first is to form by direct deposition using deposition steps. The second is to form an amorphous silicon thin film first and then use thermal energy to crystallize it into a polysilicon thin film. The third is to form an amorphous silicon thin film first. The silicon film is then crystallized into a polysilicon film using a laser. However, the above method has the following disadvantages. The disadvantage of the first method is that the polysilicon film must be deposited thick enough to form a large grain, and its surface uniformity is poor, and the required process temperature is as high as 600 degrees. Although the second method can produce a thin and uniform polysilicon film, the temperature required for the crystallization step is as high as 600 degrees, the thermal budget is high, and the required time is long, which will affect the yield. The process temperature of the third method is low. Excimer laser annealing (ELA) is traditionally used to convert amorphous silicon into polysilicon. However, the scanning speed is only 0.2mm/sec and the energy is only 370mJ/cm ² . The rate is low, limited by the size of the energy, the crystallization usually only occurs on the surface, and the purpose of recrystallizing the entire layer of amorphous silicon into polysilicon cannot be achieved. Using continuous lateral solidification (SLS) laser annealing with fast scanning speed (30mm/sec) and high laser energy (600mJ/cm ² ) to convert amorphous silicon into polysilicon can solve the above problems. However, since the thickness of the amorphous silicon thin film deposited on the edge of the glass substrate is not uniform, as shown in FIG. The amorphous silicon layer 14 in the edge area A of the glass substrate 10 will be thinner than the middle area (i.e. the main area) C. When the laser hits the thinner part of the amorphous silicon film 14, i.e. the edge area A, it will be easily damaged by the laser. . However, this area is usually where the alignment marks to be aligned in the subsequent process are placed, so it is easy to cause the interruption of the subsequent process.

As for the continuous lateral solidification (SLS) laser annealing process, since the scan rate of the SLS laser machine is as high as 30mm/sec, there must be a certain distance for acceleration, that is, it must start from outside the glass irradiated.

In order to avoid the problem that the edge area A is damaged by laser light, the current line beam laser (line beam laser) starts to irradiate from the uniform part of the amorphous silicon film 14 , that is, the main area C. Since the continuous lateral solidification (SLS) laser annealing process must be irradiated from outside the glass, the opening point of the shutter (shutter) for controlling laser radiation in the machine is set at the place where the thin film is deposited uniformly to avoid being located in the edge area A of the substrate. The amorphous silicon film 14 is damaged. As shown in Figure 1, the opening point of the shutter is set to be D and E, but the fully opening point of the shutter is d and e, so the laser energy received by the amorphous silicon thin film 14 of a section will be uneven, which reduces the available laser energy on the contrary. The area where the panel is made.

Contents of the invention

In view of this, the object of the present invention is to provide a laser annealing device that can solve the damage of the amorphous silicon layer in the edge region of the substrate during laser annealing without affecting the area that can be used to make panels.

In order to achieve the above object, the present invention proposes a laser annealing device for preparing a polysilicon film layer. This laser annealing device includes a shielding structure. The structure will resist the laser light in the edge area of the substrate, so as to prevent the laser light from fully irradiating the amorphous silicon film layer in the edge area of the substrate. Therefore, the laser beam corresponding to the edge region of the substrate will be completely blocked or partially penetrated by the shielding structure.

Description of drawings

FIG. 1 is a schematic diagram of an amorphous silicon layer conventionally deposited on a buffer layer of a glass substrate.

FIG. 2 is a schematic diagram of a laser annealing device for continuous lateral solidification (SLS) according to the present invention.

Fig. 3 is an enlarged view of the process reaction chamber in Fig. 2, wherein the shielding structure is composed of a supporting structure, a rotating device and a baffle.

FIG. 4 is a plan view of an embodiment of the shielding structure of FIG. 3 .

FIG. 5 is a plan view of another embodiment of the shielding structure of FIG. 3 .

FIG. 6 is a schematic diagram of the baffle being rotated to a position that facilitates the entry and exit of the substrate.

Fig. 7 is a structural schematic diagram of a process reaction chamber according to another preferred embodiment of the present invention, wherein the shielding structure is composed of a baffle plate and a telescopic device.

FIG. 8 is a schematic diagram showing that the baffle shrinks to a position where it is convenient for the substrate to enter and exit.

Description of figure number

Glass substrate: 10 Buffer layer: 12

Amorphous silicon layer: 14, 17 Edge area: A

Main area: C Shutter opening point: D, E

Shutter fully open point: d, e

Lasers: 22 Laser sources: 10

Attenuator: 11 Beam Homogenizer: 12

Vision Mirror: 13 Shroud: 14

Objective lens: 15 Sequence reaction chamber: 20

Transfer platform: 16 Substrate: 18

Shading structure: 21 19-1, 19-2, 19-3: Reflector

Support structure: 21b Rotation device: 21c

Bezel: 21a Support plate: 21b ₁

Support frame: 21b ₂ telescopic device: 21d

Detailed ways

In order to avoid damage to the amorphous silicon film layer in the edge region by the laser with high energy and high scanning speed, the present invention provides an improved laser annealing device to avoid laser irradiation on the amorphous silicon film layer in the edge region of the substrate, and Damage to the thinner amorphous silicon film in this area.

When the amorphous silicon film is recrystallized by continuous lateral solidification (SLS), the laser beam is first defined into a predetermined shape, and the amorphous silicon film is continuously irradiated with the laser beam. Figure 2 is a laser annealing device for continuous lateral solidification (SLS).

For the recrystallized amorphous silicon film, the undefined initial laser light 22 will be radiated from the laser source 10, and will pass through the attenuator (attenuator) 11, beam homogenizer (homogenizer) 12 and field lens (field lens), by This focuses the laser beam 22 and controls the energy of the laser beam 22 .

Next, the laser beam 22 passes through a mask 14 to define a predetermined shape. After the defined laser beam 22 passes through the objective lens (object lens) 15, the laser beam 22 can irradiate the amorphous silicon film 17 of the substrate 18 on the transfer platform 16 in the process reaction chamber 20, and it is converted into a polysilicon film, corresponding to The laser beam in the edge area of the substrate 18 is blocked by the shielding structure 21 , or partially penetrates the laser beam in this area through the shielding structure 21 . Reference numerals 19 - 1 , 19 - 2 , 19 - 3 in the figure refer to mirrors for controlling the path of the laser beam 22 .

The structure of the process reaction chamber in FIG. 2 is a preferred embodiment of the present invention, and FIG. 3 is an enlarged view of a part of the structure.

The shielding structure 21 is composed of, for example, a support structure 21b, a rotating device 21c, and a baffle 21a, wherein the support structure 21b, such as the support plate 21b ₁ in FIG. 4, or the support frame 21b ₂ in FIG. 5, is fixed to the transfer platform 16 is used to support the baffle 21a, and the baffle 21a can be fixed on the support structure 21b by the rotating device 21c, and rotated to facilitate the entry and exit of the substrate 18. FIG. 6 is a schematic diagram of the baffle plate 21 a rotating to a position where the substrate 18 can be easily moved in and out.

7 is a schematic structural view of a process reaction chamber in another preferred embodiment of the present invention. The shielding structure 21 is, for example, composed of a baffle plate 21a and a telescopic device 21d. The telescopic device 21d is, for example, fixed on the wall of the process reaction chamber for The retractable device 21d and the baffle 21a are supported, and the position of the baffle 21a can be controlled by the telescopic device 21d. FIG.

The substrate 18 can be a glass substrate, and the above-mentioned amorphous silicon film layer 17 can also be an amorphous silicon film layer of other materials, and the above-mentioned method can also be used to convert the amorphous silicon film layer into a polysilicon film layer. Usually, a buffer layer (not shown) is disposed between the amorphous silicon film layer 17 and the substrate 18 , and its material can be silicon nitride.

The above-mentioned baffle 21a is made of a material that can reflect or absorb the laser beam, so that the laser beam can be completely blocked or partially penetrated. The material is, for example, a metal material (such as chrome, aluminum, silver, etc.).

The invention improves the laser annealing device so that the laser beam does not directly irradiate the thinner amorphous silicon layer at the edge region of the substrate, so as to avoid damage to the amorphous silicon layer at the edge region due to high-energy laser irradiation.

In the present invention, the design of the baffle allows the high-scanning-speed and high-energy laser irradiation to avoid direct irradiation to the edge area, thus not reducing the area that can be used to make panels.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, this The scope of protection of the invention shall be defined by the scope of the appended patent application.

Claims (10)

1. the laser anneal device in order to the preparation polycrystalline silicon membrane is characterized in that, comprises at least:

One shifts platform, in order to place a substrate; And

One masking structure is in order to the edge zone of protection corresponding to this substrate.

2. the laser anneal device in order to the preparation polycrystalline silicon membrane as claimed in claim 1 is characterized in that this masking structure comprises:

One baffle plate; And

One supporting construction is fixed on this transfer platform, in order to support this baffle plate.

3. the laser anneal device in order to the preparation polycrystalline silicon membrane as claimed in claim 2 is characterized in that this masking structure more comprises: a whirligig in order to fixing this baffle plate on this supporting construction, and makes this baffle plate can do rotary moving.

4. the laser anneal device in order to the preparation polycrystalline silicon membrane as claimed in claim 2 is characterized in that this supporting construction is a supporting bracket or a bracing frame.

5. the laser anneal device in order to the preparation polycrystalline silicon membrane as claimed in claim 1 is characterized in that this masking structure comprises:

One baffle plate; And

One retractor device in order to supporting this baffle plate, and makes this baffle plate can do telescopic moving.

6. the laser anneal device in order to the preparation polycrystalline silicon membrane as claimed in claim 5 is characterized in that this retractor device is fixed in the wall of an operation reative cell.

7. the laser anneal device in order to the preparation polycrystalline silicon membrane as claimed in claim 1 is characterized in that having an amorphous silicon film layer on this substrate, and this amorphous silicon film layer is carried out a laser annealing by this laser anneal device, to transfer a polycrystalline silicon membrane to.

8. a method of utilizing laser crystallization to form polycrystalline silicon membrane is characterized in that, comprising:

Provide a substrate, and this substrate has an amorphous silicon film layer, this substrate is positioned over one in the operation reative cell shifts on the platform, wherein this operation reative cell comprises that more a masking structure is in order to the edge zone of protection corresponding to this substrate;

Adjust this masking structure, make this masking structure cover this fringe region corresponding to this substrate; And

This amorphous silicon film layer on this substrate is carried out laser annealing, to transfer a polycrystalline silicon membrane to.

9. the method for utilizing laser crystallization to form polycrystalline silicon membrane as claimed in claim 8 is characterized in that, carries out the method for laser annealing and anneals for using high sweep speed and high-octane laser.

10. the method for utilizing laser crystallization to form polycrystalline silicon membrane as claimed in claim 8 is characterized in that, the method for carrying out laser annealing is for using continous way lateral solidification method.

Images