JPH06291075A - Mark and method for matching and beam annealing equipment - Google Patents

Abstract

PURPOSE:To optimize positioning by applying a beam to positioning patterns on a workpiece or points in proximity thereto, and detecting the positional deviation between the positioning patterns and points irradiated with the beam. CONSTITUTION:Before regularly processing the surface of a workpiece 1, a beam is applied to positioning patterns 1P on the surface a plurality of times. The positioning patterns 1P are appropriately formed in a matching region 1X, rather than a regular processing region 1T, on the periphery of the surface. The positional deviation TLn between the positioning patterns 1P and beam- annealed lines is imaged at the several points using a video camera 7. It is then measured and computed to obtain corresponding numeric values. The angle of a mobile stage 2 is corrected to determine initial values of the stage 2 movement, and regular beam annealing is performed. This makes positioning possible based on the median of the fluctuation in beam annealing position, and reducing fraction defective.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam annealing apparatus used for manufacturing an apparatus such as an image display device having a large area and a precise pixel pattern.

[0002]

2. Description of the Related Art Conventionally, processing with an energy beam such as a laser beam has been carried out in various fields of industry. However, it is necessary to perform precise alignment in a unit of μm with respect to a pattern provided in advance on an object to be irradiated. There were few examples. In addition, even when processing is performed on such a precise pattern, it is almost the case that the entire surface of the irradiation target is irradiated with the beam at once by raster scanning or the like.

The laser beam is sometimes used for alignment in an alignment device such as a photomask aligner. In this case, by observing the reflected and scattered light of the low-energy beam on the surface of the object to be irradiated, information on the physical displacement is obtained.

[0004]

In the conventional example in which the beam irradiation is performed on the entire surface of the object to be irradiated as described above, there is no need for alignment. However, when processing with an energy beam only on a specific part within the surface of the irradiated body,
Alignment is required, which significantly degrades throughput in manufacturing and at the same time wastes energy. In addition, this method cannot be applied when there is a portion in the surface of the irradiated body that is adversely affected by the irradiation of the beam annealing.

Further, in the case of a method in which a low energy beam is used for alignment and a deviation information is obtained by observing reflected and scattered light from the surface of an object to be irradiated, it is used for actual main processing. It is difficult to completely know the information on the deviation and fluctuation that occur in the case of a high energy beam.
Therefore, when the deviation and the fluctuation cannot be ignored with respect to the required alignment accuracy, there is a problem in that sufficient accuracy cannot be obtained by the method of performing alignment with such a low energy beam.

[0006]

SUMMARY OF THE INVENTION The present invention forms a part of the surface area of an object to be processed by irradiation with a beam, and improves relative positional accuracy with respect to the area to be main processed. An alignment mark is provided which is composed of a provided pattern.

Further, as a part of a beam annealing processing method for processing with a beam, a beam is irradiated onto the alignment mark or in the vicinity thereof with respect to an irradiation target object on which the alignment mark is formed in advance, and the alignment is performed. Provided is a matching method characterized by detecting a positional deviation amount between a working mark and a portion irradiated with a beam, and optimizing alignment based on the deviation amount.

A stage, a drive system for the stage,
In a beam annealing device provided with a beam irradiation system, an imaging device, an image processing device, and a controller, preliminary beam irradiation is performed for alignment with respect to an irradiation target having the alignment mark according to claim 1. Do this on the mark or in the vicinity of the alignment mark, image the deviation amount with the image pickup device, calculate the deviation amount with the image processing device, calculate the deviation amount, and control the beam irradiation system and stage drive system from the controller. Provided is a beam annealing device for optimally aligning a beam with an object to be irradiated during processing.

The present invention relating to a matching mark and a matching method in a beam annealing technique, and a beam annealing apparatus therefor will be described below with reference to the drawings.

An object to be irradiated having alignment marks formed on its surface is placed on a stage of a beam annealing apparatus.

Next, beam irradiation is performed once or a plurality of times aiming at a positioning pattern previously formed as an alignment mark on the surface of the object to be irradiated. This preliminary beam-irradiated portion is processed in the same manner as in the main processing. Here, the number of times of preliminary beam irradiation for alignment is
It is determined by the relationship between the fluctuation of the beam position and the required alignment accuracy.

When the fluctuation of the beam position is small or the required alignment accuracy is low, the minimum number of times (ie, the two alignment patterns for the position and angle of the irradiation object and the beam irradiation system) can be grasped. ) Beam irradiation alone is sufficient. However, if the fluctuation of the beam position is large or the required alignment accuracy is severe, the number of alignment patterns that are alignment marks for beam irradiation is increased according to the degree of alignment, and the irradiation amount is calculated from the average deviation amount. Positioning accuracy can be improved by positioning the body.

However, if the number of alignment patterns to be used is increased, alignment will take time. The area cannot be increased indefinitely because it adversely affects the productivity, such as reducing the area of the originally processed portion in the surface of the irradiated body. Although it depends on the size of the substrate, the range of 3 to 6 times is preferable from the viewpoint of productivity and alignment accuracy.

The positional deviation between the alignment pattern and the beam annealed portion can be calculated by a computer after image data processing is performed by an image recognition device or the like using an image pickup device such as a video camera.

Regarding the size of the field of view of the video camera and the size of the alignment pattern, the position accuracy when the object to be irradiated is first placed on the stage is taken into consideration, and the alignment pattern and the beam are aligned within the field of view. It must be decided to enter both the illuminated parts.

From the calculated values of the shift amounts in the plurality of alignment patterns finally input to the computer and the coordinates of the alignment patterns observed in advance on the surface of the irradiation target, the irradiation target and the beam irradiation system are determined. The optimum correction amount of the position and angle deviation is calculated, and the result is output to the controller of the beam irradiation system to correct the positional relationship between the irradiation target and the beam irradiation system, and then the main processing by beam annealing is started.

The structure of the beam anneal apparatus may be either the structure in which the beam is fixed and the stage moves, the structure in which the stage is fixed and the beam moves, or the structure in which both the stage and the beam move. Any configuration may be used as long as the relationship can be corrected by the output from the controller.

The beam used may be pulsed light such as an excimer laser, continuous wave laser such as an argon ion laser or a helium neon laser, or other energy beam such as an electron beam, in combination with an object to be irradiated. The part and the non-irradiated part may be those that can be detected by an optical method such as visible light or infrared light.

The position shift detecting system may be a combination of the above-mentioned video camera and image processing device, or may be a means for detecting the reflected and scattered light of the low energy laser beam on the surface of the object to be irradiated. The calculation algorithm of the optimum correction amount of the deviation of the position and the angle between the irradiation object and the beam irradiation system may be a method of simply minimizing the average deviation, and it may be adjusted according to the position of the alignment pattern and the size of the deviation. Numerical processing such as weighting may be used.

[0020]

【Example】

(Example 1) The beam annealing method using the beam annealing apparatus of the present invention was applied to one of the manufacturing steps for manufacturing an inverted stagger type polycrystalline silicon thin film transistor substrate for driving a liquid crystal image display device. 1 is a block diagram showing the overall arrangement, FIGS. 2 to 3 are plan views of an irradiation target,
4 to 5 are partial cross-sectional views of the irradiated body. The overall outline will be described. A beam 9 was irradiated from a beam irradiation system 4 equipped with a continuous wave argon ion laser as a light source to the irradiation target 1 (amorphous silicon on a glass substrate), and linear annealing was performed (amorphous silicon was polycrystallized).

The irradiation target 1 is a 100 mm square glass substrate in which a gate insulating film, amorphous silicon, and an antireflection film are formed on a chromium thin film patterned as a gate electrode. The amorphous silicon is annealed directly by the beam 9. The irradiation target 1 was placed on the moving stage 2. Prior to the main processing on the surface of the irradiated body 1, a position which is an alignment mark appropriately disposed in a peripheral area on the surface of the irradiated body 1 in an alignment area 1X provided separately from the main processing area 1T. Beam irradiation was performed multiple times aiming at the alignment pattern.

The alignment patterns used as the alignment marks in this embodiment are substantially square figures L1, L2, ... Ln and R1, R2 ,. This is the main processing area 1T
It is possible to form a layer that functions as an alignment pattern by a masking step at the same level as the gate electrode, the source electrode, and the drain electrode by the same step as that of forming each of the constituent elements. The underlying electrode layer (such as chromium is used) is visible through the layer of amorphous silicon.

While maintaining the positional accuracy with the main processing area 1T,
An alignment region 1X is prepared at one end on the surface of the irradiation target 1,
It is located in it. Alternatively, two alignment regions 1X may be provided at both ends, and the beam irradiation directions may be alternately started when each substrate is formed. Further, square alignment patterns were formed on both ends of the alignment area 1X along the scanning direction of the beam irradiation substantially symmetrically, one at each end, and the pitch between adjacent squares was made equal.

As shown in FIG. 3, one side of a square formed as an alignment pattern has a width of 80 μm and is arranged on the left and right of the matching area 1X at a pitch of 200 μm. The size of the visual field of the video camera was adjusted so that one alignment pattern could be observed. The matching region 1X may be separated from the substrate, or may be left as it is when the area is small.

In XY scanning of beam irradiation, laser light is scanned in one direction by a scan mirror, and the moving stage 2 is moved in a direction orthogonal to the driving system 3 of the stage for a predetermined length. This was done by repeating the scanning. Laser power is 9W, irradiation target 1
The diameter of the beam 9 is about 100 μm (the beam radius or beam spot of the laser beam, the distance at which the beam amplitude becomes 1 / e times the value on the z axis), and the scanning speed of the laser beam is 1.
The moving stage 1 was stepwise moved at a pitch of 200 μm by the drive system 3 at 5 m / s, and the laser beam was irradiated as a beam.

The irradiated portion was beam annealed and polycrystallized. Here, the conditions for beam irradiation (laser power, scanning speed, etc.) were the same as those in the main processing, and the number of times was 10 times.

After the beam irradiation, the portion of the irradiated object 1 scanned by the laser beam becomes a yellow polycrystal silicon line 10 (10 lines in total) having a width of about 40 μm, which is easy to form with the unirradiated brown amorphous silicon part. I was able to determine. Then, these boundaries could be sufficiently discriminated by automatic measurement.

Misalignment of the positions of the alignment patterns L1 to Ln and R1 to Rn and the beam annealed line 10, that is, TL1 to TLn (located on the left side of FIG. 3), and TR1 to TRn. It was possible to obtain a numerical value by picking up an image (located on the right side of FIG. 3) from the video camera 7, processing the image data by the image processing device, measuring the amount of deviation, and performing arithmetic processing by the computer.

Since the positional accuracy when the irradiated object 1 is first placed on the moving stage 2 is about ± 20 μm, the positions of the alignment patterns Ln and Rn and the pre-annealed line 10 made of polycrystalline silicon in the visual field. I was able to measure the relationship. The gaps are designated as TLn and TRn, respectively.

The average of TL1 to TLn to TL10 in FIG. 2 is TLa, and the average of TR1 to TRn to TR10 is TRa. From the difference between TLa and TRa and the coordinates of the observed alignment patterns Ln and Rn in the plane of the irradiated object 1, the displacement of the position and angle is calculated, the angle of the moving stage 2 is corrected, and the moving stage 1 is moved. The initial value of was determined and the main processing was performed by the beam annealing method.

After the completion of the main processing, as a result of the inspection of 10 trial substrates, a portion where polycrystallization is required (a polycrystallized semiconductor layer finally obtained through a photolithography process or the like is It had a width of 5 μm and a pitch of 200 μm, and a total of 400 pieces).

FIG. 4 shows a sectional structure when the beam annealing of the present invention is performed in the case of the inverted stagger type. It corresponds to a cross-sectional view of the pre-annealed line 10 in FIG. In FIG. 4, the glass substrate 1A, the gate electrode 1G,
Insulating layer 1H, amorphous silicon layer 1M, anti-reflection film 1
U, the preliminary annealing line 10 and the main processing annealing line 20 are shown.

In this case, the alignment pattern 1P is formed in the same mask process as the gate electrode 1G. The difference between the alignment pattern 1P and the preliminary annealing line 10 is TL.
n (or TRn).

FIG. 5 shows a sectional structure in the case of the forward stagger type. FIG. 5 shows a glass substrate 1A, a source electrode 1S, a drain electrode 1D, an amorphous silicon layer 1
M, the antireflection film 1U, the preliminary annealing line 10, and the main processing annealing line 20 are shown. In this case, the source electrode 1
The alignment pattern 1P is formed in the same mask process as the S and drain electrodes 1D. Alignment pattern 1
The difference between P and the preliminary annealing line 10 is TLn (or TR
n).

[0035]

In the case of the processing described in the embodiments, the beam diameter (beam spot) of the laser light used for beam annealing is obtained.
The fluctuation of the irradiation position is about ± 10 μm. Further, the magnitude of the fluctuation depends on the laser power, and the larger the laser power, the larger the fluctuation.

Therefore, when the method of observing the reflected and scattered light of the low-energy laser beam on the surface of the object to be irradiated or the position alignment based on the result of only one laser beam scanning, the central value of the fluctuation is not necessarily adjusted. Even if the area to be processed by beam annealing has a considerable margin with respect to the necessary area, the necessary part was not processed and there was a considerable probability of becoming a defective product.

According to the present invention, it was possible to perform alignment with respect to the median fluctuation of the beam annealing position, and it was possible to greatly reduce the defect rate. In addition, the fluidity in the process was improved, and the throughput was dramatically improved.

Further, the present invention can be applied in various ways within a range that does not impair the effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a beam annealing apparatus of the present invention.

FIG. 2 is a plan view of an irradiation target 1 used in the present invention.

FIG. 3 is a partially enlarged plan view of an alignment mark (a) and a partially enlarged plan view of an alignment region 1X (b).

FIG. 4 is a partial cross-sectional view of an inverted stagger type TFT of the present invention.

FIG. 5 is a partial cross-sectional view of a forward stagger type TFT of the present invention.

[Explanation of symbols]

 1: irradiation target 2: moving stage 3: stage drive system 4: beam irradiation system 5: controller 6: image processing device 7: video camera 9: laser beam 10: preliminary annealing line 20: main processing annealing line

Claims (3)

[Claims] 1. A pattern which is formed in a part of a surface region of an object to be processed by being irradiated with a beam and has a positional accuracy relative to a region to be main processed. Alignment mark characterized by. 2. A part of a beam annealing method for processing with a beam, wherein a beam is irradiated onto or near the alignment mark for an irradiation target on which an alignment mark is formed in advance, and the alignment is performed. A matching method characterized in that the amount of positional deviation between the work mark and the portion irradiated with the beam is detected, and the alignment is optimized from the amount of deviation. 3. A beam annealing apparatus provided with a stage, a drive system for the stage, a beam irradiation system, an imaging device, an image processing device, and a controller.
Pre-beam irradiation is performed on or near the alignment mark for the irradiation target with the alignment mark, and the amount of deviation is imaged by the imaging device and processed by the image processing device. A beam anneal device that calculates the amount of deviation and controls the beam irradiation system and stage drive system from the controller to optimally align the beam with the irradiation target during main processing.