United States Patent c191
`Nelson
`
`[54] METHOD AND APPARATUS FOR
`PATTERNING AND IMAGING MEMBER
`
`[75]
`
`Inventor: William E. Nelson, Dallas, Tex.
`
`[73] Assignee: Texas Instrwnents Incorporated,
`Dallas, Tex.
`
`[21] Appl. No.: 361,007
`
`[22] Filed:
`
`Dec. 21, 1994
`
`Related U.S. Application Data
`
`[63] Continuation of Ser. No. 20,891, Feb. 22, 1993, abandoned,
`which is a continuation of Ser. No. 730,511, Jul. 11, 1991,
`abandoned, which is a continuation of Ser. No. 453,022,
`Dec. 20, 1989, abandoned, which is a continuation of Ser.
`No. 200,389, May 31, 1988, abandoned.
`Int. Cl.6
`... . . .. ....•. .. ..... .••... • .. ••...•. .. .. •...•... ...... . . G03F 7/20
`[51]
`[52] U.S. Cl. ......................... 430/311; 430/20; 346/107. 1;
`347/134; 358/300
`[58] Field of Search ...................... 430/20, 311; 346/160,
`346/107 R , 107.1 ; 350/338, 607, 608; 358/236,
`300; 347/134
`
`[56]
`
`References Cited
`
`U.S . PATENT DOCUMENTS
`
`I 1111111111111111 11111 lllll 111111111111111 111111111111111 IIIIII Ill lllll llll
`US005523193A
`5,523,193
`[111 Patent Number:
`[ 45] Date of Patent:
`Jun.4, 1996
`
`4,799,770
`4,818,098
`4,888,616
`5,150,250
`
`1/1989 Kahn et al .......................... 350/331 R
`4/1989 Kahn et al .
`......................... .... 353/122
`12/1989 Nanamura et al .
`................. .... 355/202
`9/1992 Setani ...................................... 359/221
`
`FOREIGN PATENT DOCUMENTS
`
`0155844
`9003621
`212843
`62-075671
`
`3/1987 European Pat. Off ..
`4/1990 Gennany .
`9/1986
`Japan ............. ......... ................. · 430/20
`4/1987
`Japan .
`
`Primary Examiner-Kathleen Duda
`Attorney, Agent, or Finn-Brain C. McCormack; James C.
`Kesterson; Richard L. Donaldson
`
`[57]
`
`ABSTRACT
`A device (40) for patterning an imaging member (46) is
`provided. The device (40) comprises a light source (42)
`which emits light rays (44). Light rays (44) pass through a
`collimator ( 45) to collimate the light rays ( 48). The light then
`strikes a spatial light modulator (50) which is controlled by
`a computer (52) to reflect the light (54). The light passes
`through an imaging member (56) to demagnify the pattern
`for striking imaging member (46). Imaging member (46) is
`thus patterned by changing modulator (50) by computer
`(52).
`
`4,793,699 12/1988 Tokuhara ................................ 350/487
`
`19 Claims, 2 Drawing Sheets
`
`52
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`COMPUTER
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`PCNA Ex. 1036
`U.S. Patent No. 9,955,551
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`

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`U.S. Patent
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`Jun.4, 1996
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`Sheet 1 of 2
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`5,523,193
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`~12
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`16
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`26
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`62
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`62
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`ro~ d'~~d,~ 1
`FIG. 3
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`66
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`66
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`64
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`66
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`FIG. 4
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`FIG. 1
`(PRIOR ART)
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`52 '-
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`COMPUTER
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`.
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`40
`~
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`FIG. 2
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`U.S. Patent
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`Jun.4, 1996
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`Sheet 2 of 2
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`5,523,193
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`104
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`102 JOO 98
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`96
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`94
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`FIG. 5b
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`FIG. 6
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`90
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`5,523,193
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`2
`from weeks to months. The total cost for creating a specific
`integrated circuit is thus a barrier to many potential users.
`Thus, there is a need for a method and apparatus for the
`fabrication of specific integrated circuits at a lower cost with
`a shorter tum-around time.
`
`SUMMARY OF THE INVENTION
`
`1
`METHOD AND APPARATUS FOR
`PATTERNING AND IMAGING MEMBER
`
`This application is a Continuation of application Ser. No.
`08/020,891 filed Feb. 22, 1993 abandoned; which is a 5
`continuation of application Ser. No. 07/730,511, filed Jul.
`11, 1991 abandoned; which is a Continuation of application
`Ser. No. 07/453,022, filed Dec. 20, 1989, abandoned; which
`is a continuation of application Ser. No. 07/200,389, filed
`May 31, 1988; abandoned.
`
`TECHNICAL FIELD OF THE INVENTION
`
`This invention relates in general to techniques for forming
`integrated circuits, and in particular to a method and appa(cid:173)
`ratus for patterning an integrated circuit on an imaging
`member with a spatial light modulator.
`
`BACKGROUND OF THE INVENTION
`
`15
`
`The present invention disclosed herein comprises a
`IO method and apparatus for patterning an imaging member
`which substantially eliminates or reduces problems associ(cid:173)
`ated with prior patterning methods and devices. The present
`invention allows the patterning of an imaging member
`without the time consuming creation of an expensive set of
`reticles, and without resorting to direct slice write proce(cid:173)
`dures using electron beam pattern generation.
`In accordance with one aspect of the invention, an appa(cid:173)
`ratus for patterning an imaging member is provided. An
`array of electronically programmable pixels on a semicon-
`20 ductor chip is illuminated by a light source. An optical
`system focuses light from the source onto the array which is
`programmed by an electronic controller. Light is reflected
`from the modulated array through an optical imager which
`focuses the light onto the imaging member to create the
`25 programmed pattern in a light sensitive layer.
`In another aspect of the present invention, the array
`comprises a linear or an area array. The imaging member
`comprises a semiconductor surface coated with photoresist,
`and the light source is ultraviolet. Alternatively, the imaging
`member may comprise a photothermal plastic surface and
`the light source may be infrared.
`It is a technical advantage of the present invention that a
`specific integrated circuit may be formed in a shorter period
`of time at a lower cost by eliminating the need for a master
`set of reticles. More than one type of device may be formed
`on a single wafer at no additional expense.
`
`The semiconductor industry is becoming highly special(cid:173)
`ized in the design of semiconductor devices. Customers are
`designing specific applications for integrated circuits such
`as, for example, for sensing temperature and fuel flow in an
`automobile to improve fuel economy. Typically, these appli(cid:173)
`cation specific integrated circuits (ASIC) are complex to
`manufacture and therefore expensive in small volumes.
`A common method of fabricating integrated circuit
`devices requires the use of a mask or reticle to photo(cid:173)
`optically transfer a pattern of a structure to a semiconductor 30
`wafer. The structure is formed by patterning a layer of
`photoresist on the semiconductor surface which is then
`etched to form the structure. An example of a photo-optical
`device used to transfer the reticle pattern to a semiconductor
`wafer is commonly termed a stepper, after the step-and- 35
`repeat exposure process utilized.
`Under present manufacturing techniques, the pattern for a
`specific integrated circuit is copied onto a computerized
`master tape. The master tape is then used to create a set of
`reticles for the lithographic process. A set of reticles is 40
`typically created with a complex, extremely expensive piece
`of equipment known as an Electron Beam Vertical Genera(cid:173)
`tor. A set of reticles must be created due to the various levels
`of structures on semiconductor devices, each of which
`requires at least one separate reticle. Reticles· cost several 45
`thousand dollars, so if there are, for example, fifteen layers
`on a particular design, the cost for reticles alone can be very
`expensive, and the time to fabricate and inspect them can be
`lengthy.
`After the reticles are created, they are sent to a fabrication
`area which uses a device such as the stepper to create the
`specific integrated circuit level by level. A reticle is placed
`into the Stepper and a photoresist coated wafer is exposed to
`a light source through the reticle. The exposure process then
`permits the subsequent development of the photoresist to
`form the desired pattern therein. The slice is then etched to
`produce a structure corresponding to the pattern.
`After each structure is etched, an operator usually inspects
`the slice for deficiencies. If a deficiency is discovered, the 60
`entire slice may be lost, the reticle must be replaced and the
`entire process started over. Thus, if an error is not detected
`until the final layer, the fabrication expense which has
`incurred is wasted.
`This process is both expensive and time consuming. The 65
`tum-around time for the creation of a master set of reticles
`and the fabrication of specific integrated circuits may be
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`For a more complete understanding of the present inven(cid:173)
`tion and for further advantages thereof, reference is now
`made to the following Detailed Description taken in con(cid:173)
`junction with the accompanying Drawings in which:
`FIG. 1 is a perspective view of a prior art Stepper;
`FIG. 2 is a perspective view of an apparatus for patterning
`an imaging member in accordance with the present inven(cid:173)
`tion;
`FIG. 3 is a plan view of a spatial light modulator with a
`linear array;
`FIG. 4 is a plan view of a spatial light modulator in an area
`array;
`FIG. 5a is a cut-away perspective of a pixel;
`FIG. Sb is a cross-sectional view of the pixel of FIG. Sa;
`55 and
`FIG. 6 is a side view of a simplified illustration of a raster.
`
`50
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`Referring to FIG. 1, an apparatus commonly termed a
`stepper is constructed in accordance with the prior art for
`patterning semiconductor devices and is generally identified
`by the reference numeral 10. The apparatus 10 comprises a
`light source 12 having a wave length suitable to expose
`organic photoresist. Light rays, as indicated by arrows 14,
`are emitted from the light source 12 in all directions.
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`Appropriate optics are provided by collimator 16 to colli(cid:173)
`mate the light rays 14 as indicated by arrows 18.
`The collimated light 18 passes through a reticle 20 which
`has been uniquely patterned by any appropriate device such
`as, for example, an Electron Beam Vertical Generator as is 5
`wen known in the art. The reticle 20 typically comprises a
`coated glass plate having patterned openings 22 therein to
`allow the collimated light 18 to pass therethrough. The light,
`as indicated by arrows 24, which passes through reticle 20
`corresponds to the desired pattern. The light 24 strikes an 10
`optical imager 26 which demagnifies the image from the
`reticle 20 and transfers the image to the wafer slice 28 as
`indicated by chip 30. The wafer 28 is coated with photoresist
`which is sensitive to the wave length of light emitted from
`the light source 12.
`The wafer slice 28 is carried by a platform 32 which is
`capable of precise movements in all directions to allow
`shifting of the slice 28 to a next position for exposure of
`additional chips as indicated by dashed lines 34.
`As an example, a reticle pattern may be ten centimeters
`(cm) square, whereas the desired pattern size on the slice
`may be one cm square. Thus, the collimator optics and the
`imager optics must be of sufficient quality to each have a
`field of view equal to the longest dimension on the reticle,
`ie. the hypotenuse of approximately fourteen cm, at the
`required level of resolution and uniformity. Additionally, the 25
`imager optics must demagnify the reticle image ten times to
`create patterns having 1 micron or smaller feature size on the
`slice. Optics having sufficient quality to meet these require(cid:173)
`ments are very complex and thus form a significant part of
`the cost of a conventional stepper.
`Often the individual chips being patterned on the slice 28
`are wider than the permissible field of view of the apparatus
`10. When the chip size is larger than the field of view, it is
`often necessary to create a mosaic of reticles to form the 35
`desired pattern at the chip level through the process of reticle
`composition. A mosaic increases the number of reticles
`required for each layer of patterns and requires special care
`to ensure continuity between each reticle making up the
`mosaic, both of which increase the time and cost of fabri- 40
`eating the integrated circuit.
`After patterning, wafer 28 is removed for developing and
`subsequent processing steps, after which wafer 28, is
`returned to the device 10 for generation of subsequent layers
`of patterns. Each layer of patterns require s a separate reticle
`or mosaic of reticles which must be installed into the device
`10. Through operator error, the reticle may occasionally be
`damaged or installed incorrectly which will destroy the
`desired pattern on wafer 28. The invention disclosed herein
`prevents these and other difficulties encountered with the
`prior art devices.
`Referring to FIG. 2, an apparatus for patterning an imag(cid:173)
`ing member constructed in accordance with the present
`invention is generally identified by the reference numeral
`40. The device 40 comprises a light source 42, for example,
`infrared, ultraviolet or x-rays, capable of emitting light rays,
`as indicated by arrows 44, having appropriate wave length
`to pattern an imaging member 46. The light 44 emitted from
`light source 42 passes through an optical device such as
`collimator 45 to redirect the light as indicated by arrows 48. 60
`Collected light 48 strikes a spatial light modulator (SLM)
`50. SLM 50 is positioned planar to the imaging member 46
`and at a predetermined angle with respect to the light source
`42. SLM 50 comprises a plurality of mirror devices or
`pixels, not shown, which will be subsequently described in 65
`more detail. A digital computer 52 is interconnected to SL M
`50 to program the pixels as required.
`
`4
`Light, as indicated by arrows 54, is reflected from SLM 50
`when selected pixel elements are actuated toward an optical
`imager 56. The optical imager 56 demagnifies the reflected
`light 54 to the proper dimensions for patterning the imaging
`member 46. The imaging member 46 comprises, for
`example, a semiconductor substrate coated with a photo-
`polymer such as photoresist or a packaged semiconductor
`chip device encased in an ablatable or photothermal plastic.
`A transporting device 58 supports and carries imaging
`member 46 in the required fashion. If imaging member 46
`is a semiconductor wafer, device 58 will comprise a platform
`for precise two dimensional movement of the slice as
`indicated by arrows X-X' and Y-Y'. If imaging member 46
`is a packaged semiconductor device, transporting device 58
`may comprise a conveyor.
`In the preferred embodiment, light source 42 comprises
`an ultraviolet light and imaging member 46 comprises a
`semiconductor wafer coated with photoresist. Device 58
`comprises a stepper type platform capable of precise two
`20 dimensional X-X' and Y-Y' movements to move the wafer 28
`in a linear or section-by-section motion.
`In accordance with the preferred embodiment of the
`present invention, a digital computer is utilized to individu(cid:173)
`ally control the pixels on the SLM. As will be subsequently
`described in greater detail, each pixel is electronically posi(cid:173)
`tioned into an on position, which will reflect light to the
`imaging member, or into an off position, which will not
`reflect light to the imaging member. B y individually con(cid:173)
`trolling each pixel, it is possible to create any pattern desired
`on the imaging member. Thus, it is possible to eliminate the
`need for unique multiple reticles as required in the prior art.
`One of the problems inherent with prior art devices was
`the time consuming reticle realignment process before pat(cid:173)
`terning subsequent layers onto an imaging member. In the
`prior art, it was necessary for an operator or optical proces-
`sor to physically align marks on the imaging member with
`a pattern on a monitor screen. Alignment was accomplished
`when the marks were positioned with respect to the screen
`pattern.
`On modem steppers, this is accomplished by computer in
`the following manner. Laser light from a separate source is
`positioned on an optical diffraction grating previously pat(cid:173)
`terned into the wafer during a prior process step. When the
`45 wafer is properly aligned, the signal from the diffracted laser
`light is maximized. This method is accurate, but require
`pre-alignment of the slice to position the laser light on the
`prescribed optical pattern on the wafer. It assumes that the
`laser system and the reticle projection system are properly
`50 registered. If the wafer is moved to a different stepper for
`later process steps, proper registration of respective layers
`may be impaired due to stepper to stepper variations. This
`method is thus susceptible to error, and is dependent on a
`precise optical grating pattern on the wafer that may, in some
`55 process steps, be affected by subsequent processing or
`material layers.
`An advantage of the present invention is that by virtue of
`the dynamic program ability of the SLM, a through-the-lens
`alignment of the wafer can be accomplished that eliminates
`the need for a separate alignment system, and guarantees
`registration of the light modulating member (SLM) to the
`imaging member regardless of intervening factors. This is
`accomplished by selectively activating elements of the SLM
`under computer control to modulate light onto the regions of
`the wafer known to contain alignment key patterns. Separate
`pixel elements on the SLM chip could be incorporated for
`this purpose, or a separate light source of a wavelength
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`chosen to not expose the photoresist could be used. When
`the wafer and the SLM chip were correctly registered, the
`return signal detected by light pattern detector 59 would give
`a suitable indication. By using the exposing element (SLM)
`to locate the imaging member 46 (wafer) misregistration, 5
`tolerances could be controlled in a highly reliable manner.
`An additional benefit in the present invention is the ability
`to pattern photoresist on an imaging member in a vacuum.
`In the prior art, it was impractical to use an evacuated
`environment due to the necessity to change reticles. In the
`present invention, reticle interchange is eliminated by the
`SLM which may therefore be installed in an evacuated
`optical system. Thus inorganic photoresist which is devel(cid:173)
`opable by short wave length light such as I-line and excimer
`laser ultraviolet and x-rays may be used to pattern a semi(cid:173)
`conductor surface in a vacuum. It was not practical, prior to
`the present invention, to use short wavelength light due to
`the attenuating influence of air in an unevacuated system. As
`is well known in the art, inorganic photoresist developed
`with short wave length light provides superior pattern reso(cid:173)
`lution.
`Referring to FIG. 3, a spatial light modulator 60 arranged
`in a linear array is shown in plan view. The linear array
`comprises a plurality of pixels 62 each approximately fifteen
`microns square, only a portion shown for ease of illustration.
`The number of pixels 62 may vary from 1,000 to over 2,400
`per inch, depending upon the use of the device. Each pixel
`62 is configured to allow movement by electrostatic control
`as will be described subsequently in more detail. Since each
`of the pixels 62 can be independently controlled between on
`and off conditions, the SLM is capable of assuming a wide
`variety of reflective configurations.
`FIG. 4 illustrates an example of an SLM 64 configured in
`an area array. The number of individual pixels 66 varies
`depending upon the use of the SLM 64. The pixels 66 are 35
`constructed in the same fashion as those in a linear array as
`will be subsequently described in more detail.
`In FIG. Sa, a partially cut-away perspective of a pixel 68
`is illustrated. A pixel of the type used herein is disclosed in
`Hornbeck U.S. Pat. No. 4 ,662,746, May 5, 1987, to Horn- 40
`beck, as typically used with an electrophotographic printing
`machine, and is incorporated herein by reference. The pixel
`68, clearly shown as mirror 70, is electro statically positioned
`into an on position or an off position by an electronic
`controller.
`The mirror 70 covers a shallow well 74 which is typically
`formed over a silicon substrate 76 which contains addressing
`logic. Substrate 76 is coated with a layer 78 of sacrificial
`material which acts as an insulator. A hinge layer 80 com- 50
`prising an aluminum/titanium/silicon (Alrfi/Si) alloy is
`formed over the layer 78. The hinge layer 80 forms the
`torsion hinges 72 about which mirror 70 pivots. A final beam
`layer 82 comprising the same Al/Ti/Si alloy as layer 78 is
`formed over layer 78. The layer 78 and the beam layer 82 are 55
`separately applied layers of the same material to minimize
`stress which could cause warping or curling of the hinges 72
`on the mirror 70.
`Plasma etch access holes 84 are provided through mirror
`70 to allow etching of the sacrificial spacer layer 78 under
`the mirror 70 to form the well 74. A plasma etch access gap
`88 formed to define the perimeter of mirror 70 also assists
`with the etching of layer 78 and allows mirror 70 to pivot
`about hinges 72.
`Referring to FIG. Sb, the pixel 68 is illustrated in cross(cid:173)
`section approximately along line Sb of FIG. Sa. Pixel 68 can
`thus be seen to comprise consecutive layers. Silicon sub-
`
`6
`strate layer 76 is coated with sacrificial spacer layer 78.
`Layer 78 is coated with a relatively thin layer of aluminum/
`titanium/silicon alloy to form hinge layer 80 which is then
`covered by a relatively thick layer of the same aluminum/
`titanium/silicon alloy to form beam layer 82. After the
`etching processes well 74 and gap 88 are formed.
`Typical dimensions for pixel 68 would be as follows:
`mirror 70 is fifteen microns square, layer 78 is four microns
`thick, hinge layer 80 is eight hundred Angstroms thick, beam
`layer 82 is thirty-six hundred Angstroms thick, access holes
`84 are two microns square, plasma etch access gap 86 is two
`microns wide and hinges 72 are three microns long and two
`microns wide.
`Silicon substrate 76 typically has addressing circuitry, not
`15 shown, formed on its surface. Pixel 68 is operated by
`applying a voltage between metal layers 80-82 and address
`electrodes on substrate 76. Mirror 70 and the exposed
`surface of substrate 76 form the two plates of an air gap
`capacitor and the opposite charges induced on the two plates
`20 by an applied voltage exert an electrostatic force attracting
`mirror 70 to substrate 76. This attractive force causes mirror
`70 to bend at hinges 72 towards substrate 76. In effect, this
`gives mirror 70 the capability of an on position or an off
`position which may be electronically controlled by a com-
`25 puter.
`Thus, in a linear array as shown on FIG. 3, the SLM will
`reflect a line of light corresponding to each pixel in an on
`position. By signalling individual pixels to be on or off, any
`variation of a straight line may be produced on an imaging
`30 member. In the area array of FIG. 4, by turning the pixels on
`or off, an area image may be formed. In both the linear and
`area arrays, it is possible to form any desired image on an
`imaging member by programming a computer to control the
`SLM.
`Referring to FIG. 6, the effects of light reflected from a
`spatial light modulator onto an imaging member to form a
`raster line is shown in greatly simplified form. A light source
`90 emits light beams 92 onto a spatial light modulator 94.
`Individual pixels 96, 98, 100, 102 and 104 are prepro(cid:173)
`grammed by an electronic controller 52 to be in the on or off
`position. In the on position, light from light source 90 is
`reflected toward imaging member 106 as shown by line 108
`from pixel 96, line 110 from pixel 100, line 112 from pixel
`102 and line 114 from pixel 104. When light strikes imaging
`member 106 an image is formed thereon as indicated by dots
`116. A pixel in the off position, as indicated by pixel 98, will
`not reflect light towards the imaging member 106 and,
`therefore, no image will be formed thereon. In actual prac(cid:173)
`tice, there could be from 1,000 to over 2,400 individual
`pixels to form images on the imaging member.
`In operation with a linear array of pixels, a linear shaped
`image or raster will be formed on imaging member 106. As
`imaging member 106 is moved, the linear images formed by
`the SLM 94 may be continuously revised by electronically
`addressing the pixels with the electronic controller. The
`electronic controller turns the individual pixels on if an
`image is to be formed and off if no image is to be formed.
`By continuously revising the SLM 94 electronically, a line
`60 of any length up to and including the entire width of imaging
`member 106 may be created. Therefore, the desired pattern
`may be created by either of two methods for moving the
`imaging member 106.
`In the preferred method, the imaging member 106 would
`65 be moved in a direction 118 perpendicular to the raster
`formed by SLM 94. The entire width of the SLM 94 is
`patterned in one continuous pass and the member 106 is then
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`7. A method for patterning an imaging member having a
`layer of photosensitive material comprising the steps of:
`selecting a frequency band from the group consisting of
`the ultraviolet, x-ray, and infrared bands;
`emitting light having a frequency within said selected
`frequency band from a source;
`optically focusing said light onto an array of electroni(cid:173)
`cally programmable mirrors;
`programming said mirrors and rotating them to an on
`position or an off position to provide a selected one of
`a plurality of patterns which may be reflected there(cid:173)
`from; and
`optically imaging said reflected pattern onto the imaging
`member to form a pattern of reacted photosensitive
`material in said layer of photosensitive material.
`8. The method of claim 7 wherein said emitted light is
`ultraviolet (UV).
`9. The method of claim 7 wherein said emitted light is
`infrared.
`10. The method of claim 7 wherein said imaging member
`is a integrated circuit chip.
`11. The method of claim 7 wherein said imaging member
`contains photothermal plastic.
`12. A method of patterning a semiconductor substrate,
`said method comprising the steps of:
`providing a digitized model of an integrated circuit;
`forming a layer of photoresist on a semiconductor sub-
`strate;
`emitting light from a source;
`optically focusing said light onto an array of electrostati(cid:173)
`cally positionable mirror devices;
`electrostatically positioning selected ones of said mirror
`devices in response to an electrical signal;
`generating said electrical signal, said electrical signal
`dependent upon said digitized model such that the
`positioning of said mirror devices corresponds to said
`digitized model; and
`optically imaging said reflected pattern onto the semicon(cid:173)
`ductor substrate to form a pattern of reacted photoresist
`in said layer of photoresist.
`13. The method of claim 12 wherein at least one of the
`steps occurs in an evacuated environment.
`14. The method of claim 13 wherein said light source
`45 provides a short wavelength light.
`15. The method of claim 14 wherein said photoresist is an
`inorganic photoresist.
`16. The method of claim 14 wherein said light source is
`the I-line of a light source.
`17. The method of claim 14 wherein said light source is
`an ultraviolet excimer laser.
`18. The method of claim 12 and further comprising the
`step of electrostatically positioning selected other ones of
`said mirror devices in response to an alignment signal and
`55 monitoring a return signal of reflected light which would
`indicate the degree of misregistration of the semi-conductor
`substrate with respect to said array of electrostatically posi(cid:173)
`tionable mirror devices.
`19. The method of claim 12 wherein the light emitted
`60 from said source has a frequency selected from the group
`consisting of the ultraviolet, x-ray, and infrared frequency
`bands.
`
`7
`stepped in a direction 120 parallel to the raster a necessary
`distance to position the next pattern. The member 106 is
`again translated in a direction 122 perpendicular to the raster
`and so on until the entire pattern is transferred to the member
`106.
`Alternatively, an area array spatial light modulator would
`create an area image which can be reprogrammed to form
`the next area image while the imaging member is stepped an
`appropriate distance in a manner analogous to the operation
`of the wafer stepper using a conventional reticle pattern.
`Although the present invention has been described with
`respect to a specific preferred embodiment thereof, various
`changes and modifications may be suggested to one skilled
`in the art and it is intended that the present invention
`encompasses such changes and modifications as fall within 15
`the scope of the appended claims.
`What is claimed is:
`1. A method for patterning an imaging member having an
`organic photoresist layer, comprising the steps of:
`emitting light from a source, said light having a short
`wavelength suitable to expose said organic photoresist
`layer on said imaging member and to render said
`organic photoresist layer sensitive to development;
`optically focusing said light onto an array of positionable 25
`mirror devices;
`positioning selected ones of said mirror devices in
`response to an electrical signal to provide a pattern
`reflected therefrom; and
`optically imaging said reflected pattern onto the imaging 30
`member to form a pattern of reacted organic photoresist
`in said organic photoresist layer.
`2. The method of claim 1, wherein the step of positioning
`said mirror devices comprises generating an electrical signal
`from an electronic controller to pivot said mirror devices, 35
`each to an on position or an off position.
`3. The method of claim 1, said method further comprising
`the step of positioning selected other ones of said mirror
`devices in response to an alignment signal and monitoring a
`return signal of reflected light, said return signal indicating 40
`the degree of misregistration of the imaging member with
`respect to said array of mirror devices.
`4 . A method for manufacturing a semiconductor device,
`comprising the steps of:
`creating a digitized model of an integrated circuit;
`programming a spatial light modulator corresponding to
`said model;
`optically focusing light from a light source onto said
`modulator;
`reflecting said light from said modulator corresponding to
`said model through an optical imager; and
`passing a photoresist coated semiconductor wafer past
`said optical imager to transfer said model to said wafer
`to form the semiconductor device.
`5. The method of claim 4, wherein the step of program(cid:173)
`ming comprises electronically controlling said modulator
`with a computer.
`6. The method of claim 5, wherein the step of electroni(cid:173)
`cally controlling further comprises electrostatically attract(cid:173)
`ing a hinged mirror about said hinge to a silicon substrate to
`position said mirror to reflect light onto said semiconductor
`wafer or to reflect light away from said semiconductor
`wafer.
`
`50
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