JP2010034404A - Laser annealing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a large type laser annealing apparatus capable of performing excellent laser annealing by preventing deflection caused by the self-weight and the resonance of a workpiece placement table. <P>SOLUTION: In the laser annealing apparatus for performing laser annealing by irradiating laser light to a workpiece placed on the movable workpiece placement table, the workpiece placement table 10 has a honeycomb structure. The honeycomb structure is composed of a honeycomb core 11, an upper plate 12 and a lower plate 13 fixed on the top and bottom of the honeycomb core and side plates 14 which are disposed and fixed so as to cover the side faces of the honeycomb core 11. Thereby, the workpiece placement table can be made light in weight and stiff, the aggravation of flatness caused by the deflection by the self-weight can be controlled, an effect of a moving device on the moving accuracy can be made small and the resonance of the workpiece placement table during the annealing can be avoided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser annealing processing apparatus that performs laser annealing on a target object, and is particularly suitable for use with a large target object.

The laser annealing treatment apparatus is used for various applications such as the production of a silicon thin film. For example, when the thin film is produced, the silicon thin film is irradiated with laser light to polycrystallize the thin film. An example of a conventional laser annealing apparatus is shown in FIG. 4, and the outline thereof will be described below.
The laser annealing processing apparatus includes a moving device 4 installed in the processing chamber 3, a target object mounting table 5 on which the target object 6 is mounted and mounted on the moving device 4, and a laser beam in the laser processing chamber 3. The optical system 2 and the laser oscillator 1 are introduced. The operation of the laser annealing processing apparatus will be described. Laser light 7 generated by the laser oscillator 1 is introduced into the processing chamber 3 through the optical system 2, and the laser light 7 is moved while moving the moving device 4 in the X and Y directions. The target object 6 on the target table 5 is irradiated to anneal the target object 6 (see, for example, Patent Document 1). At the same time, the moving device 4 operates in the Z direction to adjust the focal position of the laser beam 7.

  There are a line beam method and an SLS method in the laser annealing treatment apparatus. The line beam laser annealing apparatus shapes a laser emitted from a laser oscillator into a linear beam (line beam) by an optical system. The object to be processed on which the amorphous silicon film is formed is placed on the object processing table in the laser processing chamber, and the line beam is irradiated through the line beam optical system.

  In the conventional line beam type laser annealing treatment apparatus, there is a problem that when a laser beam having an energy higher than necessary is irradiated, silicon microcrystals are generated and the performance is remarkably deteriorated. Microcrystals are generated because nuclei for crystal growth are generated at various locations during the process of cooling the dissolved silicon. In view of this, a method for solving this problem has been proposed by reducing the width of the laser beam to several μm compared to the conventional value of about 400 μm and narrowing the region where silicon is dissolved. When a silicon thin film is irradiated with a laser having a width of several μm to completely melt the silicon thin film, when the melted region cools and crystallizes, the solid-liquid interface becomes the beginning of crystallization toward the center of the melted region. Crystal grows. Furthermore, when a laser beam patterned in a striped pattern is used to irradiate the gap, a wide area can be polycrystallized. A method of crystallizing a large area by repeating melting and crystallization in this manner is called an SLS (Sequential Lateral Solidification sequential lateral crystallization) method.

  In the silicon thin film crystallization process by the SLS method, a laser patterned to several micrometers in width must be irradiated to the silicon thin film with submicron accuracy. The laser focal depth on the crystallization process is 40 to 50 μm. However, in consideration of the thickness deviation of the object to be processed and the flatness of the object to be processed, the object to be processed must be controlled in the Z direction so that the surface of the object to be processed is positioned at the laser focal point during processing. Don't be. Accordingly, the SLS laser annealing apparatus is required to have a highly accurate moving device and automatic focus control function.

FIG. 5 shows a treatment resting table 5 used in a conventional laser annealing treatment apparatus for small and medium-sized objects. As the material, an aluminum material is often used from the viewpoint of planar workability, weight reduction, and laser resistance. The upper surface of the aluminum solid plate is processed into a flat surface, and a hole 8 for a delivery pin of an object to be processed and a back surface 9 are cut out to reduce the weight.
Japanese Patent Laid-Open No. 11-251261

  However, the laser annealing apparatus is not limited to the SLS system, and the size of the object to be processed is increased, and accordingly, the object processing table is also increased in size and weight. For this reason, the movement accuracy of the moving device on which the processing resting table is mounted is affected. In addition, the increase in size and weight deteriorates the flatness of the workpiece mounting table itself due to its own deflection, and it becomes necessary to perform automatic focus control at a higher speed. Furthermore, there arises a problem of resonance in which the end of the object mounting table shakes greatly due to the movement of the moving device in the Z direction by automatic focus control.

  In order to solve the above problems, the present invention is not limited to the SLS method, and an object of the present invention is a laser annealing apparatus capable of performing an annealing process without hindering movement accuracy of the moving apparatus and automatic focus control.

  That is, in the laser annealing apparatus of the present invention, the first aspect of the present invention is a laser annealing apparatus for performing an annealing process by irradiating a laser beam to a target object mounted on a movable target object mounting table. The to-be-processed object mounting base has a honeycomb structure.

  According to a second aspect of the present invention, in the first aspect of the present invention, the cell shape of the honeycomb core of the workpiece mounting table is a hexagon, and the cell size is 1/4 to 3/4 inch. It is characterized by being.

  According to a third aspect of the present invention, there is provided the laser annealing apparatus according to the first or second aspect of the invention, wherein the object mounting table includes a honeycomb core made of a porous body, an upper plate fixed above and below the honeycomb core, and It has a lower plate and a side plate fixed to the honeycomb core so as to cover the side surface of the honeycomb core.

  In the laser annealing treatment apparatus according to a fourth aspect of the present invention, in the third aspect of the present invention, the workpiece mounting table has a thickness of the upper plate and the lower plate of 2.5 mm to 5.0 mm. Features.

  According to a fifth aspect of the present invention, in the third or fourth aspect of the present invention, the thickness of the side plate is 4 mm to 10 mm.

  According to a sixth aspect of the present invention, there is provided the laser annealing apparatus according to any one of the third to fifth aspects, wherein the side plate is fixed to the honeycomb core together with the upper plate and the lower plate, and then the outer surface is reduced in thickness. It is characterized by cutting.

  The conditions defined in claim 2 and subsequent claims of the present invention will be described below.

Cell shape and cell size of honeycomb core: 1/4 to 3/4 inch of hexagonal shape By making the cell shape of the honeycomb core hexagonal, the strength per mass can be improved and the weight can be effectively reduced. Can do. At this time, if the hexagonal size (distance between the opposite vertices) is less than ¼, the mass per area becomes large, the weight cannot be said to be sufficient, and bending due to enlargement tends to occur. In order to prevent resonance, it is necessary to increase the resonance frequency (for example, 130 Hz or more). However, if the cell size is less than ¼, the mass increases and the resonance frequency per mass decreases. On the other hand, if the cell size exceeds 3/4, the planar processing of the upper plate and the lower plate will be affected. Moreover, the space | interval which supports the upper plate and lower plate arrange | positioned at the upper and lower sides of a honeycomb core with a cell wall becomes wide, and the workability at the time of performing a plane process in order to improve the flatness of an upper plate worsens. For this reason, the above range is desirable for the size of the hexagonal cell.

Upper plate and lower plate thickness: 2.5 mm to 5.0 mm
The upper and lower plates fixed to the top and bottom of the honeycomb core need to have a certain thickness in order to obtain the strength of the honeycomb structure. However, if the thickness is excessively thick, the mass increases and the resonance frequency per mass is low. turn into. On the other hand, if the thickness is excessively thick, the adhesiveness with the honeycomb core is deteriorated, thereby affecting the workability. For this reason, it is desirable that the thickness of the upper plate and the lower plate does not exceed 5.0 mm. Further, if the thickness of the upper plate and the lower plate is less than 2.5 mm, the rigidity of the entire object mounting table cannot be obtained sufficiently. In addition, if the upper plate and the lower plate are thin, when the upper plate and the lower plate are bonded to the honeycomb core with an adhesive or the like, the planar processing is affected by the adhesive stress. For this reason, as for the thickness of an upper board and a lower board, 2.5 mm-5.0 mm are desirable.

Side plate thickness: 4-10mm
By appropriately determining the thickness of the side plate, the balance between the mass and strength of the object mounting table can be appropriately set. Further, by increasing the resonance frequency of the object mounting table, it is possible to prevent resonance when the object mounting table moves. In addition, when the thickness of the side plate is less than 4 mm, the rigidity of the object mounting table cannot be sufficiently obtained. On the other hand, if the thickness exceeds 10 mm, the thickness of the side plate is preferably in the range of 4 to 10 mm because the occurrence of self-weight deflection or the resonance frequency is lowered to facilitate resonance during movement.

As described above, according to the present invention, in the laser annealing apparatus for performing an annealing process by irradiating a laser beam to a target object mounted on a movable target object mounting table, the target object mounting table However, since it has a honeycomb structure, the following effects are obtained.
That is, according to the present invention,
(1) By using the honeycomb structure for the target object mounting table, the target object mounting table can be made lighter and rigid, and deterioration of flatness due to its own weight deflection can be suppressed. The material of the honeycomb structure material is not particularly limited in the present invention, but a lightweight light alloy such as an aluminum material (pure aluminum or aluminum alloy) is preferable.
(2) The influence on the movement accuracy of the moving apparatus can be reduced by reducing the weight of the object mounting table.
(3) The resonance frequency of the processing object table can be increased by reducing the weight and rigidity of the processing object table. (4) By reducing the flatness of the processing object table, the automatic focus control, that is, the movement device The operation in the Z direction becomes gentle and the operating frequency band can be lowered.
(5) By increasing the resonance frequency of the object mounting table and conversely decreasing the operating frequency band in the Z direction of the moving device, resonance of the object mounting table during the annealing process can be avoided.
(6) Since a member having a low density is used, it is possible to omit the back side punching process for reducing the weight, which is performed on the small / medium-sized workpiece mounting table.

  As a result, according to the present invention, it is possible to provide a laser annealing apparatus for a large object that can be annealed without interfering with the movement accuracy and automatic focus control of the moving apparatus during the annealing process. As a result, deterioration of the performance of the annealing process due to the increase in the size of the object to be processed can be prevented, and productivity can be stabilized.

Below, one Embodiment of this invention is described based on FIGS. 1-3.
The laser annealing processing apparatus on which the object mounting table is installed has the same configuration as the conventional apparatus described based on FIG. 4 except for the object mounting table, and the description thereof is omitted. To do.
The to-be-processed object mounting base 10 has an aluminum honeycomb core 11 preferably having hexagonal cells 11a as a main structure, and the size of the cells 11a is preferably ¼ to ¾ inch. Note that the cell shape may be a triangle other than a hexagon, or a polygon such as a quadrangle.

  Similarly, an upper plate 12 and a lower plate 13 made of aluminum are fixed to the upper and lower surfaces of the honeycomb core 11. Furthermore, the side plate 14 is fixed and covered around the honeycomb core 11. Further, in some cells 11a, hexagonal cylinders 15 having the same height as the thickness of the honeycomb core 11 are arranged and fixed in the holes of the cells 11a so that no gaps are formed between the holes. A cylindrical hole of the hexagonal cylinder 15 is a hole 15a for a delivery pin of the object to be processed. The hexagonal cylinder 15 is also preferably made of lightweight aluminum. The fixing of each member can be performed, for example, by applying a thermosetting adhesive and heating.

  With the above configuration, the surface of the honeycomb core 11 is covered with the upper plate 12, the lower plate 13, the side plate 14, and the hexagonal cylinder 15 without being exposed. Accordingly, it is possible to prevent components such as an adhesive used in the honeycomb core 11, a residual solution during production, and dust generation from diffusing into the laser processing chamber 3 and contaminating the object 6 to be processed. In addition, the to-be-processed object mounting base 10 made into the honeycomb structure by the said structure is planarized with respect to the upper surface of the upper board 12, and the bottom face of the lower board 13 in order to improve flatness. In planar processing, the flatness is set to 30 μm or less. At this time, if the rigidity of the workpiece mounting table 10 is not sufficiently maintained, precise processing becomes difficult. For this reason, as shown in FIG. 3, the side plate 14 is thicker than that used as the workpiece mounting table 10, and the workpiece mounting table 10 is firmly fixed by the tool 20 or the like to perform planar processing. It is desirable to be able to However, if the side plate 14 remains thick, it becomes easy to resonate by increasing its own weight deflection or lowering the resonance frequency. Therefore, after finishing the flat surface processing, the side plate 14 is reduced in thickness by cutting the side surface to reduce the thickness. The amount of the processing body mounting table 10 is reduced.

  The to-be-processed object 10 is arrange | positioned on the moving apparatus 4 similarly to the past, and moves to X, Y, and Z direction with the moving apparatus 4. FIG. Since the workpiece mounting table 10 has a honeycomb structure, the mass per area is reduced, and sufficient rigidity is ensured. Thereby, there is no bending at the time of installing in the moving apparatus 4, and the resonance at the time of moving with the moving apparatus 4 can also be prevented effectively.

Further, since the flatness of the object mounting table can be reduced, the automatic focus control during the annealing process only needs to operate gently, and the operating frequency band in the Z direction of the moving device can be lowered to 100 Hz or less.
Furthermore, with the structure in the present embodiment, the primary resonance frequency of the object mounting table can be about 140 Hz or less, and the same vibration characteristic as that of the small and medium-sized object mounting table can be obtained.
In addition, since the operating frequency band by the automatic focus control and the resonance frequency of the object mounting table are separated, the resonance of the object mounting table due to the Z-direction operation during the automatic focus control of the moving device can be prevented.

Next, examples of the present invention will be described.
For a workpiece mounting table having an aluminum honeycomb core with a cell wall thickness of 30 to 40 μm, the cell size, upper plate thickness, lower plate thickness, and side plate thickness are changed, and the mass, deflection amount, resonance frequency, resonance per mass The frequency and workability were evaluated. The areas of the honeycomb cores were the same. The results are shown in Table 1, and each item was evaluated.

Each item was evaluated according to the following criteria.
The mass was evaluated as ◎ for 90 kg or less, ○ for over 90 kg to 120 kg, Δ for over 120 kg to 160 kg, and x for over 160 kg.
Regarding the deflection, 20 μm or less was evaluated as “◯”, 20 μm or more to 26 μm or less as “Δ”, and 26 μm or more as “×”.
The resonance frequency was evaluated as ○ for 130 Hz or more, Δ for 120 Hz to less than 130 Hz, and × for less than 120 Hz.
The resonance frequency / mass ratio was evaluated as ○ for 1.4 Hz / kg or more, Δ for 1.0 Hz / kg to less than 1.4 Hz / kg, and × for less than 1.0 Hz / kg.
The workability was evaluated by the difficulty of working to make the flatness to 30 μm or less.

In accordance with the above items, a comprehensive judgment was made according to the following criteria.
When the workability was Δ or less, the overall judgment was Δ or less. When the workability was ○, the other items were ◎ or ○ and △, and △ was 2 or more, the comprehensive judgment was △. When the workability was ◯, the other items were ◎ or ○ and △, and △ was 1, the overall judgment was ◯. All items were evaluated as ◎ if they were more than ○. If the evaluation item includes x, the overall judgment is x.
As shown in the table, in the preferred embodiment of the present invention, compared to the case where the object mounting table is made of the same material as that used for the object mounting table in the conventional medium and small-sized laser annealing apparatus. Sufficient weight reduction has been achieved. Furthermore, in the preferred embodiment of the present invention, the resonance frequency and the resonance frequency per mass can be increased to more effectively prevent resonance.

It is a longitudinal cross-sectional view of the laser annealing processing apparatus in one Embodiment of this invention. Similarly, it is a longitudinal cross-sectional view of a to-be-processed object mounting base. Similarly, it is a flowchart which shows the process at the time of plane processing. It is a longitudinal cross-sectional view of the laser annealing processing apparatus of a prior art example. Similarly, it is a longitudinal cross-sectional view of a to-be-processed object mounting base.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Optical system 3 Processing chamber 4 Moving apparatus 6 To-be-processed object 7 Laser beam 10 To-be-processed object mounting base 11 Honeycomb core 11a Cell 12 Upper board 13 Lower board 14 Side board 15 Hexagonal cylinder

Claims (6)

  In the laser annealing apparatus for performing an annealing treatment by irradiating a processing object mounted on a movable processing object mounting table with a laser beam, the processing object mounting table has a honeycomb structure. Annealing equipment.   2. The laser annealing apparatus according to claim 1, wherein the cell shape of the honeycomb core of the object mounting table is hexagonal and the cell size is 1/4 to 3/4 inch.   The object mounting table includes a honeycomb core made of a porous body, an upper plate and a lower plate fixed above and below the honeycomb core, and a side plate fixed to the honeycomb core so as to cover a side surface of the honeycomb core. The laser annealing apparatus according to claim 1, wherein the laser annealing apparatus is provided.   The laser annealing apparatus according to claim 3, wherein the workpiece mounting table has a thickness of the upper plate and the lower plate of 2.5 mm to 5.0 mm.   The laser annealing apparatus according to claim 3 or 4, wherein the side plate has a thickness of 4 mm to 10 mm.   The laser according to any one of claims 3 to 5, wherein the side plate is formed by fixing an outer surface together with the upper plate and the lower plate to the thickness after being fixed to the honeycomb core. Annealing equipment.

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