EP0165685A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Laser-based system for the total repair of photomasks
Assignee: Gould Electronics Inc
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Filing: 1985-05-01
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Granted: —
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Expires: 2005-05-01
Abstract
Abstract A low power laser-based system for repairing clear and opaque defects in a photomask. The system includes a laser source for providing a beam having a wavelength between 0.40 µm and 2.0 µm. The beam is coupled to a computer controlled scanning device which scans the beam across a defective area of the photomask to repair the defect by thermal deposition of micron-size films on the defect or by laser-induced degradation of a polymer coating the defect. Excess metal is removed from the photomask surface via laser vaporization.
Inventors
- 👤 Peter L. Young
- 👤 Modest M. Oprysko
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 04:35
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/54; G03F1/56; G03F1/68; G03F1/72
Claims Analysis
Total Claims: 57
Claim 1
Independent Claim
105 words
An instrument for repairing both clear and opaque micron-size defects in photomasks comprising: a laser source providing a beam having a wavelength between 0.40µm and 2.0µm; optical means for viewing the photomask within an optical field of view; means for locating defective areas on the photomask within the optical field of view; means for focusing the laser on the photomask; means .for precisely positioning the focused laser beam at a predetermined area on the photomask; means for continuously scanning the focused laser beam over a predetermined area; means for adjusting the laser power; and means for selecting the number of laser pulses and their duration.
Claim 2
Dependent Claim
105 words
An instrument for repairing both clear and opaque micron-size defects in photomasks comprising: a laser source providing a beam having a wavelength between 0.40µm and 2.0µm; optical means for viewing the photomask within an optical field of view; means for locating defective areas on the photomask within the optical field of view; means for focusing the laser on the photomask; means .for precisely positioning the focused laser beam at a predetermined area on the photomask; means for continuously scanning the focused laser beam over a predetermined area; means for adjusting the laser power; and means for selecting the number of laser pulses and their duration.
Claim 3
Dependent Claim
16 words
An instrument as recited in Claim 1 wherein said laser source is a solid state laser.
Claim 4
Dependent Claim
15 words
An instrument as recited in Claim 1 wherein said laser source is a gas laser.
Claim 5
Dependent Claim
42 words
An instrument as recited in Claim 1 wherein said optical means includes: a high-power focusing objective for creating an image of the photomask; a camera for receiving the image from the objective; and a monitor to display the image from the camera.
Claim 6
Dependent Claim
26 words
An instrument as recited in Claim 4 wherein said monitor provides a visual display of the defective areas of the photomask and the focused laser beam.
Claim 7
Dependent Claim
45 words
An instrument as recited in Claim 4 wherein said monitor includes a screen and further includes a numbered grid superimposed on the monitor screen to provide a means for assigning an absolute coordinate of any area of the photomask within the objective's field of view.
Claim 8
Dependent Claim
15 words
An instrument as recited in Claim 6 wherein said numbered grid is 128 x 128.
Claim 9
Dependent Claim
17 words
An instrument as recited in Claim 6 wherein said numbered grid is 512 x 512 or less.
Claim 10
Dependent Claim
23 words
An instrument as recited in Claim 1 further including a set of reflected and transmitted light optics for the illumination of the photomask.
Claim 11
Dependent Claim
30 words
An instrument as recited in Claim 1 further including a computer-controlled low resolution X, Y table for bringing the defective areas of the photomask into the optical field of view.
Claim 12
Dependent Claim
24 words
An instrument as recited in Claim 10 wherein said computer controls movement of said table using data obtained from an independent photomask inspection system.
Claim 13
Dependent Claim
31 words
An instrument as recited in Claim 11 wherein said data specifies the location of the defects on the photomask and is used by the computer to drive the X, Y stage.
Claim 14
Dependent Claim
33 words
An instrument as' recited in Claim 1 further including a high-power objective wherein the focusing of the laser beam on the photomask is accomplished by directing the beam through a high power objective.
Claim 15
Dependent Claim
18 words
An instrument as recited in Claim 1 wherein said objective has a numerical aperature of 0.2 or higher.
Claim 16
Dependent Claim
17 words
An instrument as recited in Claim 1 wherein said objective has a magnification of 20x or higher.
Claim 17
Dependent Claim
27 words
An instrument as recited in Claim 13 further includes table adjustable in the X-Y and Z planes for facilitating focusing of the laser beam onto the photomask.
Claim 18
Dependent Claim
21 words
An instrument as recited in Claim 16 wherein the table is used to change the distance between the photomask and objective.
Claim 19
Dependent Claim
30 words
An instrument as recited in Claim 13 further including a piezoelectric driver on which the objective is mounted for the fine control of the distance between the objective and photomask.
Claim 20
Dependent Claim
16 words
An instrument as recited in Claim 18 further including a computer for controlling the piezoelectric driver.
Claim 21
Dependent Claim
17 words
An instrument as recited in Claim 1 further including a computer-controlled scanning/positioning device for positioninng the laser.
Claim 22
Dependent Claim
15 words
An instrument as recited in Claim 20 wherein said scanning/positioning device is an acousto-optic device.
Claim 23
Dependent Claim
18 words
- 22. An instrument as recited in Claim 20 wherein said laser scanning device is an electro-optic device.
Claim 24
Dependent Claim
16 words
An instrument as recited in Claim 20 wherein said laser scanning device is a mechanical device.
Claim 25
Dependent Claim
42 words
An instrument as recited in Claim 20 further including a television monitor for determining the coordinates of the defect to produce data to be fed into the computer to control the scanning/positioning device direct the focused laser beam on to the defect.
Claim 26
Dependent Claim
23 words
An instrument as recited in Claim 1 wherein said means for continuously scanning the laser beam includes a computer controlled laser scanning device.
Claim 27
Dependent Claim
14 words
An instrument as recited in Claim 20 wherein said laser scanning device is acousto-optic.
Claim 28
Dependent Claim
14 words
An instrument as recited in Claim 20 wherein said laser scanning device is electro-optic.
Claim 29
Dependent Claim
24 words
An instrument as recited in Claim 20 wherein said scanning device moves said laser in a boustrophedonic path across the surface of the defect.
Claim 30
Dependent Claim
59 words
An instrument as recited in Claim 25 further including means for dividing the defect area into one or more predetermined areas and for determining the coordinates for each area, said means including a television monitor and wherein said coordinates are fed into said computer for controlling the scanning device and continuously scans the focused laser beam over the defect.
Claim 31
Dependent Claim
22 words
An instrument as recited in Claim 29 wherein the predetermined area is less than or equal to a 128pm x 128µm area.
Claim 32
Dependent Claim
22 words
An instrument as recited in Claim 29 wherein the predetermined area is less than or equal to a 512pm x 512µm area.
Claim 33
Dependent Claim
20 words
An instrument as recited in Claim 1 wherein said means for adjusting the laser power is a computer controlled modulator.
Claim 34
Dependent Claim
12 words
An instrument as recited in Claim 32 wherein said modulator is acousto-optic.
Claim 35
Dependent Claim
12 words
An instrument as recited in Claim 32 wherein said modulator is electro-optic.
Claim 36
Dependent Claim
28 words
An instrument as recited in Claim 32 wherein said computer control can adjust the laser power at the surface of the photomask between 0.01 milliwatt and 100 milliwatts.
Claim 37
Dependent Claim
22 words
An instrument as recited in Claim 1 further including a computer controlled modulator for generating laser pulses of adjustable number and duration.
Claim 38
Dependent Claim
12 words
An instrument as recited in Claim 36 wherein the modulator is acousto-optic.
Claim 39
Dependent Claim
22 words
An instrument as recited in Claim 36 wherein the laser pulse duration is selected within the range of 1µsec to 1 sec.
Claim 40
Dependent Claim
158 words
An instrument for repairing a defective area of a photomask, the photomask having a novolak-based polymer coating thereon, comprising: a laser source for providing a beam having a wavelength between 0.4µm and 2.0µm; means for scanning said beam across the defective area of the photomask for localized heating thereof to darken the polymer; means for detecting the level of darkening of the polymer to provide a signal representative thereof; control means for controlling the power of said laser source; and means responsive to said darkening level signal for controlling the power level of the laser beam to heat the polymer to a temperature between 200°C and 500°C to brown the polymer, said control means increasing the power leve of the laser beam to heat the polymer to a temperature greater than 500°C to darken the polymer when the darkening level signal indicates browning of the polymer so thatt the optical density is at least as great as 2.5.
Claim 41
Dependent Claim
158 words
An instrument for repairing a defective area of a photomask, the photomask having a novolak-based polymer coating thereon, comprising: a laser source for providing a beam having a wavelength between 0.4µm and 2.0µm; means for scanning said beam across the defective area of the photomask for localized heating thereof to darken the polymer; means for detecting the level of darkening of the polymer to provide a signal representative thereof; control means for controlling the power of said laser source; and means responsive to said darkening level signal for controlling the power level of the laser beam to heat the polymer to a temperature between 200°C and 500°C to brown the polymer, said control means increasing the power leve of the laser beam to heat the polymer to a temperature greater than 500°C to darken the polymer when the darkening level signal indicates browning of the polymer so thatt the optical density is at least as great as 2.5.
Claim 42
Dependent Claim
127 words
An instrument for repairing a clear defect on a photomask, the photomask being positioned in a cell containing a metal-bearing gaseous compound, comprising: a laser source for providing a beam having a wavelength between 0.40µm and 2.0um; means coupled to said laser source for scanning and positioning said beam across a clear defect of the photomask; means coupled to said laser source for positioning said beam at a clear defect of the photomask; and means coupled to said scanning and positioning means for focusing said beam on the clear defect surface of the photomask for localized heating of an area of the substrate to which said laser beam is incident to thermally decompose molecules of said compound on the heated area to deposit a metal film thereon.
Claim 43
Dependent Claim
127 words
An instrument for repairing a clear defect on a photomask, the photomask being positioned in a cell containing a metal-bearing gaseous compound, comprising: a laser source for providing a beam having a wavelength between 0.40µm and 2.0um; means coupled to said laser source for scanning and positioning said beam across a clear defect of the photomask; means coupled to said laser source for positioning said beam at a clear defect of the photomask; and means coupled to said scanning and positioning means for focusing said beam on the clear defect surface of the photomask for localized heating of an area of the substrate to which said laser beam is incident to thermally decompose molecules of said compound on the heated area to deposit a metal film thereon.
Claim 44
Dependent Claim
21 words
An instrument for photomask repair comprising first means for repairing micron-sized clear defects; and second means for repairing micron-sized opaque defects.
Claim 45
Dependent Claim
21 words
An instrument for photomask repair comprising first means for repairing micron-sized clear defects; and second means for repairing micron-sized opaque defects.
Claim 46
Dependent Claim
20 words
An instrument as recited in Claim 41 wherein said first means and said second means are accomplished using a laser.
Claim 47
Dependent Claim
22 words
An instrument as recited in Claim 42 wherein said laser provides a beam having a wave-length between 0.4 microns and 2.0 microns.
Claim 48
Dependent Claim
37 words
An instrument as recited in Claim 44 further including an optical means for viewing the photomask within an optical field of view; and means for locating defective areas on the photomask within the optical field of view.
Claim 49
Dependent Claim
20 words
An instrument as recited in Claim 44 including means for continuously scanning the focused laser beam of a predetermined area.
Claim 50
Dependent Claim
20 words
An instrument as recited in Claim 41 including means for continuously scanning the focused laser beam of a predetermined area.
Claim 51
Dependent Claim
24 words
An instrument as recited in Claim 42 further including means for precisely positioning a focused laser beam at a predetermined area on the photomask.
Claim 52
Dependent Claim
23 words
An instrument as recited in Claim 42 further including a means for focusing the laser on the photomask in a diffraction-limited spot size.
Claim 53
Dependent Claim
15 words
An instrument as recited in Claim 42 wherein said laser source is a solid-state laser.
Claim 54
Independent Claim
199 words
A method for repairing clear and opaque defects on a photomask comprising: coating said photomask with a polymer; positioning said photomask with respect to a laser source such that a beam from said laser source is focused on a clear defect on said photomask; scanning said beam across said clear defect to produce localized heating of said polymer to darken the polymer; detecting the level of darkening of the polymer to provide a signal representative thereof; means for responding to said darkening level signal for controlling the power level of the laser beam to heat the temperature between 200°C and 500°C to brown the polymer; further increasing the power level of the laser to heat the polymer to a temperature greater than 500°C to darken the polymer when the darkening level signal indicates browning of the polymer until the optical density of the polymer is at least as great as 2.5; repositioning the photomask with respect to said laser source such that a beam from said laser source is focused on an opaque defect on said photomask; adjusting the power to ablate photoresist covering the opaque defect; readjusting the laser power to vaporize the metalization forming the opaque defect.
Claim 55
Independent Claim
199 words
A method for repairing clear and opaque defects on a photomask comprising: coating said photomask with a polymer; positioning said photomask with respect to a laser source such that a beam from said laser source is focused on a clear defect on said photomask; scanning said beam across said clear defect to produce localized heating of said polymer to darken the polymer; detecting the level of darkening of the polymer to provide a signal representative thereof; means for responding to said darkening level signal for controlling the power level of the laser beam to heat the temperature between 200°C and 500°C to brown the polymer; further increasing the power level of the laser to heat the polymer to a temperature greater than 500°C to darken the polymer when the darkening level signal indicates browning of the polymer until the optical density of the polymer is at least as great as 2.5; repositioning the photomask with respect to said laser source such that a beam from said laser source is focused on an opaque defect on said photomask; adjusting the power to ablate photoresist covering the opaque defect; readjusting the laser power to vaporize the metalization forming the opaque defect.
Claim 56
Dependent Claim
166 words
An instrument for repairing a clear defect and an opaque defect on a photomask, the photomask being positioned in a cell containing a metal-bearing gaseous compound, comprising: a laser source for providing a beam having a wavelength between 0.40µm and 2.0pm; means coupled to said laser source for scanning and positioning said beam across a clear defect of the photomask; means coupled to said laser source for positioning said beam at a clear defect of the photomask; means coupled to said scanning and positioning means for focusing said beam on the clear defect surface of the photomask for localized heating of an area of the substrate to which said laser beam is incident to thermally decompose molecules of said compound on the heated area to deposit a metal film thereon; means for venting said cell to remove said gaseous compound from said cell; means for scanning and positioning said laser beam across an opaque defect of the photomask to vaporize the metalization causing the opaque defect.
Claim 57
Dependent Claim
166 words
An instrument for repairing a clear defect and an opaque defect on a photomask, the photomask being positioned in a cell containing a metal-bearing gaseous compound, comprising: a laser source for providing a beam having a wavelength between 0.40µm and 2.0pm; means coupled to said laser source for scanning and positioning said beam across a clear defect of the photomask; means coupled to said laser source for positioning said beam at a clear defect of the photomask; means coupled to said scanning and positioning means for focusing said beam on the clear defect surface of the photomask for localized heating of an area of the substrate to which said laser beam is incident to thermally decompose molecules of said compound on the heated area to deposit a metal film thereon; means for venting said cell to remove said gaseous compound from said cell; means for scanning and positioning said laser beam across an opaque defect of the photomask to vaporize the metalization causing the opaque defect.
References Cited (Backward Citations)
No citation records indexed.
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