Pattern generator

• US 20080079922A1
• Filed: 10/31/2007
• Published: 04/03/2008
• Est. Priority Date: 03/02/1998
• Status: Active Grant

• Current Assignee: Torbjorn Sandstrom
• Original Assignee: Torbjorn Sandstrom
• Inventors: Sandstrom, Torbjorn
• Granted Patent: US 7,800,815 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/064 by means of optical elements, e.g. lenses, mirrors or prisms
• CPC Class Codes: B23K 26/0648 comprising lenses
• CPC Class Codes: B41J 2/465 using masks, e.g. light-switching masks
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 27/0043 in projection exposure systems, e.g. microlithographic systems
• CPC Class Codes: G02B 27/4205 having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
• CPC Class Codes: G03F 7/2022 Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure
• CPC Class Codes: G03F 7/70041 by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/704 Scanned exposure beam, e.g. raster-, rotary- and vector scanning mask projection exposure involving relative movement of patterned beam and workpiece during imaging G03F7/70358
• CPC Class Codes: G03F 7/70475 Stitching, i.e. connecting image fields to produce a device field, the field occupied by a device such as a memory chip, processor chip, CCD, flat panel display
• CPC Class Codes: G03F 7/70725 control
• CPC Class Codes: G09G 3/2007 Display of intermediate tones
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: H04N 1/195 the array comprising a two-dimensional array or a combination of two-dimensional arrays
• CPC Class Codes: H04N 2201/0414 Scanning an image in a series of overlapping zones
• CPC Class Codes: H04N 5/7458 the modulator being an array of deformable mirrors, e.g. digital micromirror device [DMD]

Abstract

The present invention relates to an apparatus for creating a pattern on a workpiece sensitive to radiation, such as a photomask a display panel or a microoptical device. The apparatus may include a source for emitting light flashes, a spatial modulator having modulating elements (pixels), adapted to being illuminated by the radiation, and a projection system creating an image of the modulator on the workpiece. It may further include an electronic data processing and delivery system receiving a digital description of the pattern to be written, converting the pattern to modulator signals, and feeding the signals to the modulator. An electronic control system may be provided to control a trigger signal to compensate for flash-to-flash time jitter in the light source.

Claims

1-19. -19. (canceled)

20. A method for creating a microlithographic pattern on a workpiece sensitive to radiation using a spatial light modulator (SLM) having a plurality of modulating elements with adjoining stationary areas, the modulating elements, the method comprising:

reading, from an information storage device, a pattern description describing geometry of a binary pattern for features of a semiconductor device with an address grid unit in a range of 1 nm to 100 nm;

extracting a sequence of partial patterns from the pattern description;

converting said partial patterns to modulator signals;

operating at least some of the modulating elements so that the piston elements are driven to phases relative to the adjoining stationary areas to produce a desired intensity;

emitting electromagnetic radiation in the wavelength range from extreme ultraviolet (EUV) to infrared (IR);

illuminating the SLM using said radiation;

projecting the illumination from the SLM onto the workpiece forming a partial image; and

moving at least one of said workpiece and projection system relative to each other while coordinating the movement, the operation of modulating elements and intensity of the radiation such that said pattern is stitched together from the partial images created by the sequence of partial patterns.

21. The method of claim 20, wherein the SLM includes a one-dimensional micromirror matrix.

22. The method of claim 20, wherein the SLM includes a two-dimensional micromirror matrix.

23. The method of claim 20, wherein the electromagnetic radiation is in the wavelength range of between 13 nm and 370 nm, inclusive.

24. The method of claim 20, wherein the converting the partial patterns further includes,

converting the binary pattern data into a gray-scaled bit map from which the modulator signals are derived.

25. A method of optical printing using an SLM in a system including an optical system for projecting an image of the SLM onto a workpiece that is positioned on a moving stage, the method comprising:

selectively illuminating portions of the SLM, a first part of the SLM being loaded with data while a second part of the SLM is illuminated; and

printing a pattern on the workpiece with radiation modulated using the SLM.

26. The method of claim 25, wherein the printing on the workpiece as the moving stage transports the workpiece relative to the projected image of the SLM.

27. The method of claim 25, further including,

scanning the SLM using a continuous laser source.

28. The method of claim 25, further including,

scanning the SLM at a repetition rate of greater than or equal to 100 kHz.

29. The method of claim 25, further including,

controlling the scanning of the SLM using an electro-optic scanner.

30. The method of claim 25, further including,

controlling the scanning of the SLM using an acousto-optic scanner.

31. The method of claim 25, wherein the SLM is a micro-mirror array.

32. The method of claim 26, wherein the SLM is a two dimensional array rotated so that a coordinate system of the SLM is not parallel to a direction of relative motion of the workpiece during the printing.

33. The method of claim 32, wherein the coordinate system of the SLM is rotated 45 degrees to the direction of the relative motion of the workpiece.

34. An apparatus for creating a pattern on a workpiece sensitive to light radiation, the apparatus comprising

a source for emitting electromagnetic radiation in a wavelength range from EUV to IR;

a spatial light modulator (SLM) having a plurality of modulating elements operable for being illuminated by said radiation;

a projection system for creating an image of the modulator on the workpiece;

an electronic data processing and delivery system for receiving a digital description of the pattern, converting said pattern to modulator signals, and sending said signals to the modulator;

a precision mechanical system for positioning at least one of said workpiece and said projection system relative to each other;

an electronic control system controlling the position of the workpiece, the sending of the signals to the modulator and the intensity of the radiation, such that said pattern is printed on the workpiece;

wherein

the input pattern description is converted to modulator voltages for particular pixels to correct for variation among pixels using a lookup memory.

35. The apparatus according to claim 34, wherein the lookup memory is updated to compensate for changes in responses of the particular pixels.

36. The apparatus according to claim 35, wherein the lookup memory is updated iteratively.

37. The apparatus according to claim 35, wherein the changes are time dependent.

38. A method for creating a pattern on a workpiece sensitive to light radiation, the method comprising

emitting electromagnetic radiation on a spatial light modulator (SLM) having a plurality of modulating elements, the electromagnetic radiation being in a wavelength range from EUV to IR;

creating an image of the SLM on the workpiece using a projection system;

converting a received digital description of the pattern into modulator signals, the received digital description of the pattern being converted to modulator voltages for particular pixels to correct for variation among pixels using a lookup memory;

sending said signals to the modulator;

positioning at least one of said workpiece and said projection system relative to each other; and

controlling the position of the workpiece, the sending of the signals to the modulator and the intensity of the radiation, such that said pattern is printed on the workpiece.

39. The method according to claim 38, wherein the lookup memory is updated to compensate for changes in responses of the particular pixels.

40. The method according to claim 39, wherein the lookup memory is updated iteratively.

41. The apparatus according to claim 40, wherein the changes are time dependent.

42. A method for printing a pattern on a workpiece, the method comprising:

first exposing, during a first pass, the workpiece to a first intensity of electromagnetic radiation to create a first portion of the pattern on the workpiece;

measuring, during the first exposure, the actual intensity of the electromagnetic radiation used during first pass; and

second exposing, during a second pass, the workpiece to a second intensity of the electromagnetic radiation for actual printing of the pattern based on the measured actual intensity.

43. The method of claim 42, wherein the electromagnetic radiation is extreme ultra violet light (EUV).

44. The method of claim 42, further comprising:

generating the electromagnetic radiation using an excimer laser.

45. The method of claim 42, wherein the workpiece is exposed using a spatial light modulator (SLM).

46. The method of claim 42, wherein the first intensity of the electromagnetic radiation being 90% of the second intensity for actual printing of the pattern.

47. The method of claim 42, wherein the second exposure is made with nominally 10% exposure.

48. The method of claim 42, wherein the second exposure is made 5-15% of the second intensity for actual printing of the pattern depending on the measured actual intensity of the electromagnetic radiation used during the first pass.

49. The method of claim 42, wherein the second exposure is made 5-15% of the second intensity for actual printing of the pattern by the use of modulation.