JP2015082551A - Laser irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser irradiation device capable of suppressing deterioration of focus accuracy that is caused by position deviation between a measurement position recognized by a system controller and an actually measured position.SOLUTION: A surface height measuring apparatus is relatively moved along a measurement line set on the surface of an object to be processed and is moved in a reverse direction on an adjacent measurement line to actually measure the surface height of the object to be processed before laser irradiation, and the actually measured surface height is memorized. A plurality of actually measured surface heights in the vicinity of a laser irradiation position are read out, and the surface height of the laser irradiation position is calculated based on a plurality of these actually measured surface heights. Actually measured surface heights on a plurality of measurement lines near the laser irradiation position are included in a plurality of the actually measured surface heights. On measurement lines adjacent to each other, position deviation between the measurement position recognized by the system controller and the actually measured position is reversed. Since the surface of the object to be processed can be considered a plane, if the position deviation is reversed, errors caused by position deviation is offset when calculating the surface height. Thereby, deterioration of focus accuracy can be suppressed.

Description

  The present invention relates to a laser irradiation apparatus, and more particularly, to a laser irradiation apparatus that can suppress a reduction in focus accuracy due to a positional deviation between a measurement position recognized by a system controller and an actually measured position.

  A laser irradiation device that irradiates a laser beam by relatively moving the focus lens system along a scanning line set on the surface of the object to be processed and focusing the surface of the object to be processed by the focus lens system, and scanning before the laser irradiation. The surface height of the workpiece on the line is measured with a surface height measuring instrument, and the measured surface height is stored. When the focus lens system reaches the irradiation position on the scanning line during laser irradiation, There is known a laser irradiation apparatus of a type in which the measured surface height is read and focused to irradiate laser light (see, for example, Patent Documents 1 and 2).

JP 2010-258257 A JP 2006-32843 A

When actually measuring the surface height of the workpiece on the scan line, there is a delay time from when the system controller commands the measurement until the actual measurement is performed by the surface height measuring instrument. Since the surface height measuring device relatively moves between the measurement positions, a displacement occurs between the measurement position recognized by the system controller and the actually measured position. This positional deviation increases as the relative movement speed of the surface height measuring instrument increases.
However, since the conventional laser irradiation apparatus has not been processed in consideration of this positional deviation, there is a problem that the focusing accuracy is lowered.
Accordingly, an object of the present invention is to provide a laser irradiation apparatus capable of suppressing a decrease in focus accuracy due to a positional deviation between a measurement position recognized by a system controller and an actually measured position.

In a first aspect, the present invention relates to laser irradiation in which a focus lens system is relatively moved along a scanning line set on the surface of a workpiece, and the focus lens system is focused on the surface of the workpiece to irradiate laser light. A device that measures the surface height of a workpiece before laser irradiation by relatively moving the surface height measuring device along the measurement line set on the surface of the workpiece and in the opposite direction on the adjacent measurement line. Actual surface height measuring means for storing the actual surface height, and a plurality of actual surface heights in the vicinity of the irradiation position including the actual surface heights on the plurality of measurement lines close to the irradiation position on the scanning line. A surface height calculating means for calculating the surface height of the irradiation position based on the actually measured surface height, and a focus for focusing on the surface height of the irradiation position when irradiating laser light at the irradiation position. To provide a laser irradiation apparatus characterized by comprising a scrap control means.
In the above configuration, the scanning line and the measurement line are virtual lines.
In the laser irradiation apparatus according to the first aspect, the surface height of the workpiece is measured before laser irradiation, a plurality of measured surface heights in the vicinity of the laser irradiation position are read, and the plurality of measured surface heights are read. Based on this, the surface height of the laser irradiation position is calculated. Here, the plurality of measured surface heights include measured surface heights on a plurality of measurement lines close to the laser irradiation position. In the adjacent measurement line, the surface height measuring instrument is relatively moved in the reverse direction, so that the positional deviation between the measurement position recognized by the system controller and the actually measured position is in the reverse direction. It has become. Since the surface of the object to be processed can be regarded as a flat surface on average, if the positional deviation is in the reverse direction, the error due to the positional deviation is canceled when calculating the surface height of the laser irradiation position. Therefore, it is possible to obtain an effect capable of suppressing a decrease in focus accuracy caused by the position shift. In addition, even if an abnormal value is mixed in the measured surface height, an effect of suppressing the influence can be obtained.

In a second aspect, the present invention provides a laser irradiation apparatus according to the first aspect in which the relative movement speed of the surface height measuring device during surface height measurement is higher than the relative movement speed of the focus lens system during laser irradiation. Provided is a laser irradiation apparatus characterized by being slower.
In the laser irradiation apparatus according to the second aspect, the relative movement speed (for example, 180 mm / second) of the focus lens system at the time of laser irradiation can be determined from the viewpoint of performing processing appropriately in as short a time as possible. From the viewpoint of appropriately measuring the height, the relative moving speed (for example, 100 mm / second) of the surface height measuring device can be determined.

In a third aspect, the present invention provides the laser irradiation apparatus according to the first or second aspect, wherein the interval between the measurement lines is narrower than the interval between the scanning lines. To do.
In the laser irradiation apparatus according to the third aspect, the distance between the scanning lines (for example, 6 mm) can be determined based on the size of the laser spot (for example, 8 mm) in the direction in which the plurality of scanning lines are arranged, and the measurement point density can be increased. From the measurement line can be determined (for example, 5 mm).

In a fourth aspect, the present invention provides the laser irradiation apparatus according to any one of the first to third aspects, wherein the surface height calculation means is a measured surface height on the four measurement lines closest to the irradiation position. Then, a total of 20 actually measured surface heights of five closest to the irradiation position on each measurement line are read out, and the surface height of the irradiation position is calculated based on those actual surface heights. A laser irradiation apparatus characterized by the above is provided.
In the laser irradiation apparatus according to the fourth aspect, it is possible to suppress a decrease in focus accuracy in the direction in which a plurality of measurement lines are arranged by the same action as in the first aspect. Furthermore, since a plurality of measured surface heights are used also in the measurement line direction, even if an abnormal value is mixed in the measured surface height, the influence can be suppressed.

  According to the laser irradiation apparatus of the present invention, an error caused by a positional deviation between the measurement position recognized by the system controller and the actually measured actual position is removed when calculating the surface height of the laser irradiation position. Therefore, it is possible to suppress a decrease in focus accuracy.

1 is a configuration explanatory diagram illustrating a laser irradiation apparatus according to Embodiment 1. FIG. It is explanatory drawing which shows the measurement line set to the surface of a workpiece. It is a conceptual diagram which shows the position shift between the measurement position which the system controller has recognized, and the actual measurement position actually measured. It is explanatory drawing which shows the scanning line set on the surface of the workpiece. It is a conceptual diagram which shows the several measurement surface height read in order to calculate the surface height of a laser irradiation position. It is a conceptual diagram which shows the example by which the error by position shift is canceled.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.

Example 1
FIG. 1 is a configuration explanatory diagram illustrating a laser irradiation apparatus 100 according to the first embodiment.
The laser irradiation apparatus 100 includes a laser oscillator 1, an attenuator 2, a mirror 3 that reflects a laser beam, a beam shaper 4 for forming a laser spot W having a predetermined shape, a focus lens system 5, and a surface height. A surface height measuring device 6 that measures the surface height of the workpiece B at the measurement position D and outputs a surface height signal, and a stage 7 on which the workpiece B is placed and moved in the x and y directions. The x direction moving motor 8, the y direction moving motor 9, the x direction moving driver 10, the y direction moving driver 11, the control of the laser oscillator 1, the control of the focus lens system 5, and the control of the x direction moving motor 8. And a system controller 12 for controlling the y-direction moving motor 9 and the like.

The workpiece B is, for example, a substrate in which an amorphous silicon semiconductor layer is formed on a glass substrate. The length in the x direction is 470 mm and the length in the y direction is 300 mm.
Laser irradiation is an annealing process for forming an amorphous silicon semiconductor layer into a polycrystalline silicon semiconductor layer.

  As shown in FIG. 2, measurement lines d1 to d6 are virtually set on the surface of the workpiece B. Although not shown, the actual number of measurement lines is, for example, 60, and the measurement line pitch dy is, for example, 5 mm.

Before performing laser irradiation, the system controller 12 moves the workpiece B along the measurement lines d1 to d6 by the stage 7 and in the opposite direction to the surface height measuring device 6 in the opposite direction. The surface height of the object B is measured, and the measured surface height is stored in association with the measurement position (indicated by a white circle in FIG. 2).
The speed at which the workpiece B is moved along the measurement lines d1 to d6 in order to actually measure the surface height of the workpiece B is, for example, 100 mm / second, and the measurement cycle is, for example, 50 ms. Although not shown, the actual number of measurement positions on one measurement line is 94, for example, and the measurement position pitch dx is 5 mm, for example.

As shown in FIG. 3, between the measurement position recognized by the system controller 12 (indicated by a white circle in FIG. 3) and the actually measured position (indicated by a black square in FIG. 3). Has a displacement Δ. This is because there is a delay time between the system controller 12 instructing the measurement and the actual measurement by the surface height measuring device 6, and the surface height measuring device 6 is also in the delay time. This is because the workpiece B moves.
If the delay time is 10 ms, for example, the positional deviation Δ is 1 mm, for example.

As shown in FIG. 4, scanning lines L <b> 1 to L <b> 6 are virtually set on the surface of the workpiece B. Although not shown, the actual number of scanning lines is, for example, 50, and the scanning line pitch Py is, for example, 6 mm.
The laser spot W refers to a shape of a region where the laser light intensity is, for example, 90% or more of the top flat intensity, and is, for example, a linear shape having a width Wx = 0.06 mm in the x direction and a width Wy = 8 mm in the y direction.

When performing laser irradiation, the system controller 12 moves the processing object B along the scanning lines L1 to L5 and in the opposite direction with respect to the focus lens system 5 by the stage 7 to perform processing on the processing object. The surface of B is irradiated with a laser spot W.
The speed at which the workpiece B is moved along the scanning lines L1 to L5 to irradiate the workpiece B with laser is, for example, 180 mm / second, and the irradiation cycle is, for example, about 0.17 ms. Although not shown, the actual number of irradiation positions on one scanning line is, for example, about 15666, and the irradiation position pitch is, for example, 0.03 mm.

As shown in FIG. 5, the system controller 12 calculates the surface height of the workpiece B at a certain irradiation position as follows.
(1) A measurement position closest to the irradiation position (= the position of the center point R of the laser spot W and indicated by a black triangle in FIG. 5) on the front side in the scanning traveling direction (indicated by p in FIG. 5). )
(2) On the measurement line including the measurement position p (d3 in FIG. 5), two measurement positions sandwiching the measurement position p are obtained.
(3) On one measurement line (d2 in FIG. 5) on the front side in the scanning direction from the measurement line d3 and on two measurement lines (d4 and d5 in FIG. 5) on the rear side in the scanning direction from the measurement line d3, ( Five measurement positions each corresponding to the five measurement positions in 2) are obtained.
(4) The actually measured surface height (= black square included in the region A in FIG. 5) stored in association with the 20 measured positions (= white circles included in the region A in FIG. 5) is read.
(5) An arithmetic process such as a median filter or an averaging filter is applied to the read actual surface height, and the surface height at the irradiation position R is calculated. When the irradiation position approaches the edge of the workpiece B, 20 actual measured surface heights cannot be obtained. In this case, for example, a median filter is used depending on the obtained measured surface height arrangement. And the averaging filter is changed to perform arithmetic processing.

  When irradiating the laser spot W, the system controller 12 provides the focus lens system 5 with the calculated surface height of the workpiece B at each irradiation position, and performs focus control.

FIG. 6 is a conceptual diagram illustrating an example in which an error due to misalignment is canceled.
The surface of the workpiece B is a flat surface having a gradient in the x direction.
As shown in FIG. 6A, in the measurement line d3, an error δ (d3) is generated from the surface height at the measurement position p due to the positional deviation Δ from the measurement position p.
As shown in FIG. 6B, in the measurement line d4, an error δ (d4) is generated from the surface height at the measurement position q due to the positional deviation Δ from the measurement position q.
Since the error δ (d3) on the measurement line d3 and the error δ (d4) on the measurement line d4 are opposite, the actual surface height on the measurement line d3 and the actual surface height on the measurement line d4 are averaged, for example. Then, the error δ (d3) and the error δ (d4) are canceled out.

According to the laser irradiation apparatus 100, the following effects can be obtained.
(A) The 20 measured surface heights included in the area A in FIG. 5 include those whose displacement is in the opposite direction, but the surface of the workpiece B is flat on average. Therefore, errors caused by misalignment are canceled out in the opposite directions. Accordingly, it is possible to suppress a decrease in focus accuracy caused by a positional deviation between the measurement position recognized by the system controller 12 and the actually measured position.
(B) Since a plurality of actually measured surface heights are used also in the measurement line direction, even if an abnormal value is mixed in the actually measured surface height, the influence can be suppressed.

  In the above description, the surface height of the irradiation position R is calculated from the measured surface heights on the four measurement lines closest to the irradiation position R. However, two or more lines closest to the irradiation position R (from the viewpoint of error cancellation) The surface height at the irradiation position R may be calculated from the actually measured surface height on the measurement line. Further, the surface height of the irradiation position R was calculated from the five actually measured surface heights closest to the irradiation position R on one measurement line, but the irradiation was performed from two or more actual measurement surface heights closest to the irradiation position R. The surface height of the position R may be calculated.

  The laser irradiation apparatus of the present invention can be used for, for example, a process of forming an amorphous silicon semiconductor layer formed on a glass substrate into a polycrystalline silicon semiconductor layer.

DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Attenuator 3 Mirror 4 Beam shaper 5 Focus lens system 6 Surface height measuring instrument 7 Stage 8 X direction moving motor 9 Y direction moving motor 10 X direction moving driver 11 Y direction moving driver 12 System controller B Work object D Surface height measurement position d1 to d6 Measurement line L1 to L5 Scan line R Irradiation position p, q Measurement position W Laser spot

Claims (4)

A laser irradiation apparatus for irradiating a laser beam by relatively moving a focus lens system along a scanning line set on the surface of the processing object and focusing the surface of the processing object with the focus lens system, the surface of the processing object The surface height measuring device is relatively moved along the measurement line set in the opposite direction and in the opposite direction, the surface height of the workpiece is measured before laser irradiation, and the measured surface height is stored. A plurality of measured surface heights near the irradiation position, including the measured surface height measuring means and the measured surface heights on the plurality of measurement lines close to the irradiation position on the scanning line, based on the measured surface heights Surface height calculating means for calculating the surface height of the irradiation position, and focus control means for focusing on the surface height of the irradiation position when irradiating laser light at the irradiation position. The laser irradiation apparatus according to claim and. 2. The laser irradiation apparatus according to claim 1, wherein the relative movement speed of the surface height measuring device at the time of measuring the surface height is slower than the relative movement speed of the focus lens system at the time of laser irradiation. apparatus. 3. The laser irradiation apparatus according to claim 1, wherein an interval between the measurement lines is narrower than an interval between the scanning lines. 4. The laser irradiation apparatus according to claim 1, wherein the surface height calculation means includes actual measurement surface heights on four measurement lines closest to the irradiation position and each of the measurement lines. A laser irradiation apparatus characterized in that a total of 20 actually measured surface heights of five closest to the irradiation position are read out, and the surface height at the irradiation position is calculated based on these actual surface heights.

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