JPH079882B2 - Attitude control method for optical window - Google Patents

Description

TECHNICAL FIELD The present invention relates to a posture control method for an optical window that always holds the optical window attached to a chamber or the like in a fixed posture.

(Prior art) Silicon wafer processing and TFT for liquid crystal display
(Thin Film Transistor) In manufacturing and the like, film formation is conventionally performed by forming a film while laser annealing.

The film is formed by setting the substrate in the chamber and using the gas CVD method.When laser annealing is also used, the workpiece in the chamber is irradiated with laser light through the optical window provided in the chamber. Then do.

In the conventional film forming process using laser annealing, when irradiating a laser beam on a workpiece such as a silicon wafer, the laser beam is scanned on the workpiece by shaking the spot beam laser beam to anneal the entire workpiece. It is being processed.

Since recent semiconductor devices or liquid crystal displays have been highly integrated, extremely high position accuracy is required for laser beam irradiation position accuracy during film formation.

(Problems to be Solved by the Invention) By the way, when a laser beam is shaken with respect to an optical window as in a conventional laser annealing apparatus, refraction occurs when the laser beam incident on the optical window passes through the optical window. To wake up
Even if the light beam is made incident in a predetermined direction, the light beam cannot be condensed at a regular position on the work piece. As a result, there is a problem that an error occurs in the processing accuracy of the workpiece.

When the film is formed by using the laser annealing together, the chamber is maintained in a considerably high vacuum, so that an optical window having a relatively large thickness and pressure resistance is used. Therefore, an error due to refraction when the laser light obliquely enters the optical window cannot be ignored in manufacturing a semiconductor device or the like.

In addition, since these vacuum devices have rotary pumps and other sources of vibration, it is necessary to compensate for these vibrations and ensure reliable laser light irradiation in order to enable extremely accurate machining. There is.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an optical window in an apparatus having an optical window for incident light, such as a laser annealing apparatus. On the other hand, it is an object of the present invention to provide a posture control method for an optical window that allows light to be incident at a constant incident angle.

(Means for Solving the Problems) The present invention has the following configuration in order to achieve the above object.

That is, in an attitude control method of an optical window for holding an optical window for entering light such as laser light in a constant attitude so that the incident light is incident at a constant incident angle, a movable support such as a bellows is provided for the optical window. The attitude control coil and a magnet facing the attitude control coil are provided on the outer peripheral side of the optical window while being supported on the optical window, and a laser beam is projected as reference light on the optical window, and the laser beam of the optical window The reflection position is constantly detected by the light receiving position detector, the deviation of the posture of the optical window from the normal position is detected based on the detection result by the light receiving position detector, and the posture control coil is energized based on the detection result. Is controlled to return the optical window to a normal position, and the attitude of the optical window is constantly controlled.

(Examples) Hereinafter, preferred examples of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory view showing a posture control method of an optical window according to the present invention.

In this embodiment, laser light A for annealing a workpiece is made to enter the optical window 10 from a direction perpendicular to the optical window 10 so that the laser light A always enters the optical window 10 vertically. Is controlling the attitude of.

The optical system that causes the laser light A to enter the optical window 10 is
Is placed so that the laser beam A is correctly vertically incident in a state where is in a regular position. For example, a normal position is determined by irradiating a laser spot on the position of the workpiece and calibrating the spot position.

The laser beam B for monitoring the deviation of the attitude of the optical window 10 with respect to the laser beam A has a different optical path from that of the laser beam A.
To irradiate.

Reference numeral 12 is a half mirror prism provided on the side of the optical path of the laser light A, 14 is a mirror installed at a position above the optical window 10 so as not to block the laser light A, and 16 is provided behind the half mirror prism 12. It is a light receiving position detector.

A laser beam different from the laser beam A, for example, a He-Ne laser when an Ar laser is used as the laser beam A, is made incident on the half mirror prism 12 to make the half mirror prism 12
After being reflected by 12, the light is reflected by the mirror 14 and projected near the center of the optical window 10.

The light reflected on the surface of the optical window 10 is reflected by the mirror 14, passes through the half mirror 12, and is received by the light receiving position detector 16. The light receiving position detector 16 is composed of a plurality of light receiving elements and detects the incident position of the reflected beam.

The optical window 10 is supported by a movable support 20 such as a welded bellows which is fixed to a chamber containing a workpiece. An attitude control coil 22 is fixed to a flange 21 that holds the outer peripheral portion of the optical window 10 at a position where the flange 21 is equally divided in the circumferential direction.
A magnet 24 is fixed to the machine frame and arranged on the outer side facing each attitude control coil 22. The flange 21 is suspended from a machine frame by using a metal wire to prevent the movable support 20 from wobbling.

26 is a control unit for controlling the attitude of the optical window 10, which analyzes the light receiving signal by the light receiving position detector 16,
The attitude of the optical window 10 is controlled by controlling the power supply to the attitude control coil 22 based on the analysis result.

That is, first, an optical system such as the mirror 14 for projecting the laser beam B onto the optical window 10 is set at the center of the light receiving position detector 16 simultaneously with the alignment of the laser beam A or with the optical section 10 in the normal position. Set so that the spot reflects and returns.

In a processing step such as laser annealing, some external vibration occurs, which causes the optical window 10 to slightly tilt from the normal position. Then, since the incident angle of the laser beam B on the optical window 10 changes, the return optical path of the laser beam B deviates from the regular optical path, and the spot position deviates from the center on the light receiving surface of the light receiving position detector 16 as shown in the figure. become. Since the deviation in the light receiving position detector 16 can be recognized in which direction the optical window 10 is tilted depending on the deviation direction, the optical window 10 may be returned in the direction to restore the deviation. That is, the positional deviation of the optical window 10 is analyzed based on the received light signal of the light receiving position detector 16, and according to the result, the plurality of attitude control coils 22 provided on the outer peripheral side of the optical window 10 are appropriately energized. , The reflected light of the laser light B is made to coincide with the regular position of the light receiving position detector 16. Since the movable support 22 is movable in any direction, the attitude control coil 22
By energizing, the movable support 22 moves correspondingly to return the optical window 10 to the normal position.

In the case of this method, the optical window 10 can be instantly restored to the normal position on the basis of the detection signal of the light receiving position detector 16 like the voice coil, and there is a feature that the followability is good, and external vibration or the like occurs. Even when there is an influence, the light receiving position detector 16 constantly monitors the light receiving position, so that the attitude of the optical window 10 can be always kept constant.

By holding the optical window 10 in a fixed direction as described above, the laser light A is always incident perpendicularly to the optical window 10 and the laser light A is incident on the optical window 10 during the processing of the workpiece. The error due to oblique incidence can be eliminated, and more accurate processing can be performed.

FIG. 2 is a block diagram showing an embodiment of a laser annealing apparatus to which the above attitude control method for optical windows is applied. 30 in the figure
Is a chamber for accommodating a workpiece, and a welding bellows is attached to the upper opening of the chamber 10 as a movable support 20 of the optical window 10. The arrangement of the attitude control coil 22 and the like is similar to that described above.

An XY stage 34 for supporting a work piece 32 is installed in the chamber 30. 36 is a drive unit for driving the XY stage 34, and 38 is a controller for controlling the drive unit 36. The XY stage 34 is supported by a magnetic levitation method and is pulse-controlled by the controller 38.

The exhaust system of the chamber 30 is constituted by a rotary pump 40 and a turbo molecular pump 42. 44 is a conductance valve,
Reference numeral 46 is an opening / closing valve, and 48 is a leak valve 30.

50 is a preliminary vacuum tank for cleaning the surface of the workpiece 32 by housing the workpiece 32 and pulling it to a vacuum, and 52 is a transport unit for transporting the workpiece.

Reference numeral 54 is a gas line for supplying a film forming gas to the chamber 30. 56 is a gas flow meter, and 58 is a mass flow controller for adjusting the gas flow rate.

In the embodiment, the chamber 30 is supported by being floated from the machine frame, and a vibration control mechanism is provided so that the vibration of the rotary pump 40, the turbo molecular pump 42, etc. does not affect the chamber 30 as much as possible.

The laser light for processing the workpiece 32 is the optical window.
It is injected from 10 into the chamber 30. 60 is a continuous-wave Ar laser used in the annealing treatment, 62 is a power supply unit to the Ar laser 60, 64 is an optical system for making the laser light incident vertically on the optical window 10 and condensing it on the workpiece 32, 66 is a power meter for monitoring the laser light intensity, and 68 is a signal processing system. Reference numeral 70 is a half mirror placed in the optical path of the laser light to monitor the laser light intensity.

Reference numeral 80 is a He-Ne laser used for controlling the attitude of the optical window 10. The laser light emitted from the He-Ne laser 80 is reflected by the half mirror prism 12 and the mirror 14 and projected onto the optical window 10.

When laser annealing is performed by this laser annealing apparatus, the laser beam from the Ar laser 60 is applied to the workpiece 32 through the optical window 10, and the XY stage 34 is driven to drive the workpiece 32 on the workpiece 32. Scanning with laser light is performed. When performing laser annealing at the same time as film formation, use a gas line
From 54, a gas for film formation is introduced into the chamber 30, and a film is formed by an appropriate method such as a CVD method, and the film is formed by irradiating laser light.

The attitude control of the optical window 10 is performed according to the above-mentioned method.
This is done by monitoring the laser light. By controlling the attitude of the optical window 10 accurately, it is possible to perform extremely high-precision processing, and even when processing a large-area object, fine processing is possible. Particularly, in the case of the present embodiment, the workpiece 32 is moved to XY as described above.
The object 32 to be processed is moved by placing it on the stage 34, and the laser light is made incident perpendicularly to the optical window 10 from a fixed position. Therefore, it is possible to eliminate the influence of refraction of the laser light on the optical window, which is more preferable. Is. By controlling the attitude of the optical window 10 at a constant level, a uniform irradiation accuracy can be obtained over the entire workpiece even when laser annealing is performed by linearly irradiating an extremely large workpiece with laser light. It has a feature that it enables highly accurate processing.

Further, in this embodiment, the laser light intensity is constantly monitored by the power meter 66 in order to make the thermal energy of the laser light applied to the workpiece 32 constant, and when the laser light intensity decreases, X
-When the moving speed of the Y stage 34 is slowed down and the laser light intensity becomes high, the moving speed of the XY stage 34 is increased to compensate for the fluctuation of the laser light intensity so that a constant laser annealing can be performed. ing.

The above-described method for controlling the attitude of the optical window can be applied not only to the laser annealing apparatus but also to various general apparatuses having an optical window, and when it is necessary to eliminate the influence of external vibration on the optical window. The attitude of the optical window can be controlled by a similar method.

Although the present invention has been variously described above with reference to the preferred embodiments, the present invention is not limited to these embodiments.
Of course, many modifications can be made without departing from the spirit of the invention.

(Effect of the Invention) According to the attitude control method of the optical window according to the present invention, when the optical window is deviated from the regular position due to the influence of external vibration or the like, the compensation function acts to return the optical window to the regular position. Thus, the optical window can always be held at a fixed position. As a result, the light irradiation to the object to be processed is accurately performed, and it is possible to achieve a remarkable effect such that the processing can be performed with higher accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory view for explaining a posture control method for an optical window according to the present invention, and FIG. 2 is a block diagram showing an example of an apparatus to which this method is applied. 10 ... Optical window, 12 ... Half mirror prism, 14 ... Mirror, 16 ... Receiving position detector, 20 ... Movable support, 22 ...
Attitude control coil, 24 Magnet, 30 Chamber, 32 Workpiece, 34 XY stage, 40 Rotary pump, 42 Turbo molecular pump, 50 Preliminary vacuum chamber , 52 …… Transport unit, 54 …… Gas line, 60 ……
Ar laser, 62 ... Power supply unit, 64 ... Optical system, 66 ...
Power meter, 80 ... He-Ne laser.

Claims (1)

[Claims] 1. An attitude control method for an optical window, wherein an optical window for entering light such as laser light is held in a constant attitude so that the incident light is incident at a constant incident angle. An attitude control coil and a magnet are installed on the outer peripheral side of the optical window so as to be supported by a movable support and face the attitude control coil, project laser light as reference light on the optical window, and The reflection position of the laser light is constantly detected by the light receiving position detector, the deviation of the attitude of the optical window from the normal position is detected based on the detection result by the light receiving position detector, and the attitude control is performed based on the detection result. An attitude control method for an optical window, characterized in that the attitude of the optical window is controlled at all times by controlling energization to a coil to return the optical window to a normal position.