Source: http://www.google.com/patents/US6381002?dq=6335678
Timestamp: 2017-08-22 04:10:42
Document Index: 165001318

Matched Legal Cases: ['arts 20', 'art 20', 'arts 20', 'arts 20', 'art 20', 'art 20']

Patent US6381002 - Process for controlling a gap between a mask and a workpiece in proximity ... - Google Patents
A process and device are provided for controlling a gap between a mask and a workpiece in a proximity exposure device in which there are only a few processes of measurement of the exposure gap and parallel adjustment, in which even for a large workpiece the gap between the mask and the workpiece can...http://www.google.com/patents/US6381002?utm_source=gb-gplus-sharePatent US6381002 - Process for controlling a gap between a mask and a workpiece in proximity exposure and a proximity exposure device
Publication number US6381002 B1
Application number US 09/343,710
Publication number 09343710, 343710, US 6381002 B1, US 6381002B1, US-B1-6381002, US6381002 B1, US6381002B1
Inventors Shinji Suzuki
US 6381002 B1
1. A process for controlling a gap between a mask and a workpiece in a proximity exposure device, comprising the steps of:
providing a device for moving a workpiece carrier, said device including a first movement device for moving a first carrier up and down and a second movement device, the second movement device being located on a carrier driven by the first movement device and including several workpiece carrier support parts which move the workpiece carrier up and down and control a slope of the workpiece carrier;
placing an alignment workpiece on the workpiece carrier and raising the workpiece carrier using the first movement device to a position at which a gap between a bottom of a mask and a top of the alignment workpiece located on the workpiece carrier has a size that can be measured;
measuring the size of the gap at several locations;
recording a position of each of the workpiece carrier support parts as a respective parallel zero point in a control element after movement of the several workpiece carrier support parts of the second movement device is executed such that the workpiece carrier is located parallel to the mask;
removing the alignment workpiece from the workpiece carrier and providing each of the workpiece carrier support parts in a standby state after respective movement to respective parallel zero points recorded in the control element;
mounting a workpiece to be exposed on the workpiece carrier while the workpiece carrier support parts are in said standby state at said respective parallel zero points recorded in the control element;
raising the workpiece to be exposed by means of the first movement device until an alignment gap position is reached; and
adjusting the slope of the workpiece carrier using the second movement device and raising the workpiece to be exposed until an exposure gap position which is parallel to the mask is reached.
2. A proximity exposure device in which a mask and a workpiece are brought close to one another, exposure light is emitted via the mask onto the workpiece and a mask pattern is transferred to the workpiece, comprising:
a first movement device for moving a first carrier up and down with respect to a base;
a second movement device including several workpiece carrier support parts which move a workpiece carrier up and down with respect to the first carrier and adjust a slope of the workpiece carrier, the workpiece carrier support parts each including a workpiece carrier support component which moves integrally with the workpiece carrier, a drive part for driving the respective workpiece carrier support component and a means for determining the position of the respective workpiece carrier support component up and down;
means for measuring the size of a gap, between the mask and a workpiece on the workpiece carrier, at several locations; and
a control element which controls the drive of the first and the second movement devices, the control element including a memory means for recording a position of parallel zero points of the respective workpiece carrier support component which places the workpiece carrier parallel to the mask, wherein the control element is adapted to move the respective workpiece carrier support component to the position of parallel zero points which have been recorded in the memory means and thereby shift the respective workpiece carrier support component into a standby state, wherein the first movement device is adapted to cause the workpiece carrier to approach the mask, and the second movement device is adapted to adjust the slope of the workpiece carrier.
The Z-carrier ZS is furthermore located over a bearing 16 in a guide 15 which is located perpendicular to the base plate BP. The guide 15 controls the direction of motion in the X-direction and the Y-direction such that the Z-carrier ZS does not move in the X-Y direction when it moves in the Z-direction (X: for example to the right and left in the drawings, Y: the direction perpendicular to the page of the drawing). The guide 15 controls movement in the X-direction. In the direction sloped 90° in this respect, there is a guide which controls movement in the Y-direction.
Recently there has been a trend for workpieces to become larger. Especially in the area of liquid crystal substrates, large substrates, measuring 550 mm×650 mm to 650 mm×830 mm, are becoming more important. Furthermore there is a growing demand for an exposure gap of less than or equal to 50 microns in order to enable exposure with high precision.
In the parallel adjustment by one such mechanical method, however, the disadvantages are as follows. For a large workpiece carrier of a device in which large liquid crystal substrates are exposed, the labor input is considerable. There are cases in which the slope is in the 500 micron range. Furthermore, the thickness tolerance of a large glass plate is generally ±50 microns. When the workpiece carrier WS is moved all at once, until a gap of, for example, less than or equal to 550 microns is achieved, which is smaller than the sum of the accuracy (500 microns) for mechanical, parallel adjustment and thickness tolerance (±50 microns) of the glass plate, there are therefore cases in which the edge of the workpiece W collides with the mask M. To prevent this contact of the workpiece W with the mask M, in a state in which there is a gap of greater than or equal to the above described gap (550 microns), tentative parallel arrangement is done, afterwards the gap is set smaller, and a parallel arrangement is done again. This process is repeated until the desired gap, i.e. 40 microns, is formed in parallel. But in this case, the gap measurement and measurement of the parallel adjustment must be repeated again and again. Therefore, a large amount of time for adjusting the exposure gap, and great skill for measurements and the adjustment activity, is needed.
FIGS. 2 and 3 schematically show the mask M, the workpiece carrier WS and the Z2-movement device D2 in an enlarged representation. FIGS. 4 (a) and (b) each show the arrangement of the workpiece carrier support parts 20 and the gap measurement means 1. As is illustrated in FIGS. 2 and 3, in the workpiece carrier support part 20, there is a sensor 20 c which determines the position of the workpiece carrier support component 20 a. The output of the sensor 20 c is sent to the control element 5 shown in FIG. 1. The workpiece carrier support components 20 a can be driven for example by a servomotor provided with a coder. The output of the coder is used as the output of the sensor 20 c.
As is shown in FIG. 4 (a) and FIG. 4 (b), in this embodiment, the workpiece carrier support parts 20 are located at three points on the Z-carrier ZS. Furthermore, above the positions at which the workpiece carrier support parts 20 are installed, the gap measurement means 1 is located perpendicular thereto.
l=650 microns, m=630 microns, n=600 microns This shows that the workpiece carrier WS is tilted by 50 microns with reference to the mask M at points a to c. Since the workpiece carrier WS becomes parallel to the mask M when l=m=n, the amount of movement of the respective workpiece carrier support component 20 a is input in the control element 5 such that 50 microns lifting is done at point a with respect to the workpiece carrier support component 20 a and 30 microns lifting is done at point b with respect to the workpiece carrier support component 20 a.
(7) A control means 5 b for the Z2-movement device of the control element 5 drives the servomotor of the drive part 20 b until the output of the encoder installed in the servomotor of the workpiece carrier support part 20 reaches a number of pulses corresponding to the above described amount of motion. Thus the workpiece carrier support components 20 a are moved. After movement, the distance between the mask M and the workpiece W is measured once again by the gap measuring means 1. The above described adjustment and measurements are repeated until the parallelism reaches an allowable range.
(3) The intermediate movement carrier 11 of the Z1-movement device D1 is driven by a control means 5 a for the Z1-movement device of the control element 5. The Z-carrier ZS moves in the Z-direction. As a result, the workpiece carrier WS is moved in the Z-direction and is raised at high speed until an alignment gap (for example 100 microns) is reached within the focal depth of an alignment microscope with a magnification factor of 1 to 3× that of the first stage of positioning (alignment) of the mask M to the workpiece W. A magnification factor of 1 to 3× means that the images of the articles to be viewed (alignment marks) on a CCD camera of the alignment microscope are projection magnified by 1 to 3 times.
(5) When the substrate becomes even larger and when the undulations of the substrate become larger, the alignment of the mask M to the workpiece W is done as follows. First, positioning by the alignment microscope is done with 1 to 3× at a gap width between the mask M and the workpiece W of 300 microns. Next, positioning by the alignment microscope of 10× is done at a gap width of 100 microns up to the exposure width (for example 40 microns).
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Cooperative Classification G03F9/00, G03F7/70691, G03F9/7038, G03F9/703
European Classification G03F9/70B8, G03F9/70B6G, G03F7/70N, G03F9/00
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