WO1997046914A1 - Procede de fabrication d'un dispositif a circuit integre a semiconducteur, photomasque et procedes de fabrication d'un photomasque - Google Patents

Procede de fabrication d'un dispositif a circuit integre a semiconducteur, photomasque et procedes de fabrication d'un photomasque Download PDF

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Publication number
WO1997046914A1
WO1997046914A1 PCT/JP1996/001513 JP9601513W WO9746914A1 WO 1997046914 A1 WO1997046914 A1 WO 1997046914A1 JP 9601513 W JP9601513 W JP 9601513W WO 9746914 A1 WO9746914 A1 WO 9746914A1
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WO
WIPO (PCT)
Prior art keywords
pattern
transmittance
photomask
mask
wafer
Prior art date
Application number
PCT/JP1996/001513
Other languages
English (en)
Japanese (ja)
Inventor
Susumu Komoriya
Shinji Kuniyoshi
Osamu Suga
Nobuyuki Iriki
Morihisa Hoga
Masamichi Kobayashi
Hisashi Maejima
Original Assignee
Hitachi, Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi, Ltd. filed Critical Hitachi, Ltd.
Priority to PCT/JP1996/001513 priority Critical patent/WO1997046914A1/fr
Publication of WO1997046914A1 publication Critical patent/WO1997046914A1/fr

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70425—Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
    • G03F7/70433—Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/50—Mask blanks not covered by G03F1/20 - G03F1/34; Preparation thereof
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70425—Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
    • G03F7/70433—Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
    • G03F7/70441—Optical proximity correction [OPC]

Definitions

  • the present invention relates to an exposure technique, and relates to a method of manufacturing a semiconductor integrated circuit device having a step of transferring a pattern of a semiconductor integrated circuit to a semiconductor wafer, a photomask used therefor, and a method of manufacturing the same.
  • a semiconductor integrated circuit device is manufactured by forming a pattern such as a circuit and a wiring on a semiconductor wafer.
  • the semiconductor integrated circuit device has a process of processing a wafer, and an assembling process of cutting a semiconductor chip from the wafer and assembling the semiconductor chip in a package.
  • the basic steps of wafer processing include oxidation processing to form an oxide film on the surface of the wafer, sputtering processing to form a thin film on the surface of the wafer using the sputtering phenomenon, and gas phase or chemical processing.
  • thin film forming process such as CVD process to form thin film on wafer surface by reaction
  • resist coating process to apply hot resist solution on wafer
  • pattern such as circuit and wiring of semiconductor integrated circuit device
  • the photoresist film is exposed to ultraviolet light using a photomask on which the patterned mask pattern is formed.
  • the resist film is exposed to light, the resist film is developed, and the resist film is developed.
  • a microfabrication process such as an etching process for removing the component, and a doping process for doping impurities by implanting a thermal diffusion method on a wafer.
  • the light transmitted through the opening in the mask becomes wider on the wafer than the mask pattern due to the limitation of the resolution limit in the reduction optical system. Since the light from each opening is in phase, they interact with each other to strengthen each other.As a result, the contrast of the light intensity distribution on the wafer becomes insufficient and the patterns are separated from each other. You will not be able to do so.
  • the phase shift mask is provided with a transparent film that is formed in the mask and that inverts the phase in one of the openings adjacent to each other. Interactions that cancel each other out work. As a result, the light intensity at the pattern boundary becomes zero, and the pattern can be separated.
  • a negative resist solution is used.
  • As the pattern formed on the surface of the wafer a number of linear line patterns for forming wirings and circuits are formed in parallel through linear space patterns, and are repeated.
  • a repetitive pattern, also called a pattern is formed so as to be continuous with any one of the line patterns in the repetitive pattern, and only the line pattern is provided in isolation in a surplus region of the wafer, that is, a ground portion.
  • the phase shift mask is effective when a wafer is exposed to a repetitive pattern in which a plurality of line patterns and space patterns are repeated in parallel with each other.
  • it is not effective when exposing an isolated line or space pattern, and the actual semiconductor integrated circuit pattern is a phase shift because a repetitive pattern, an isolated line pattern, and an isolated space pattern are mixed.
  • the pattern repeats with isolated line or space patterns.
  • the resolution characteristics differ depending on the return pattern, and the degree of freedom in pattern design is limited.
  • Japanese Patent Laid-Open Publication No. Hei 6-313964 discloses a pattern forming method by projection exposure of an oblique incident illumination system using a transflective phase shift mask.
  • the isolated line pattern is transferred to the wafer with a larger thickness than the repetitive pattern. Conversely, when the ⁇ value is large, The isolated line pattern becomes thinner. From the viewpoint of the repetition pattern resolution and the depth of focus, it is desirable that the threshold value is large. However, when the ⁇ value is increased, the isolated line pattern becomes too thin.
  • An object of the present invention is to provide a technique capable of transferring a pattern of a semiconductor integrated circuit device having a line pattern and a space pattern onto a semiconductor wafer with high resolution.
  • Another object of the present invention is to transfer a pattern of a semiconductor integrated circuit device in which a repetitive pattern in which a line pattern and a space pattern are repeated, an isolated line pattern and an isolated space pattern are mixed on a semiconductor wafer with high resolution. It is to provide technologies that can be used.
  • Still another object of the present invention is to provide a technique capable of increasing the degree of freedom in designing circuits and wiring patterns of a semiconductor integrated circuit device.
  • a method of manufacturing a semiconductor integrated circuit device includes a line pattern transferred to a semiconductor wafer and a mask pattern corresponding to a space pattern. Corresponding to the minimum transmittance portion with the smallest transmittance, the slit-shaped maximum transmittance portion formed outside the minimum transmittance portion and having the largest transmittance, and the minimum transmittance portion and the maximum transmittance portion.
  • a method of manufacturing a semiconductor integrated circuit device includes a mask pattern corresponding to a repetition pattern, an isolated line pattern, and an isolated space pattern transferred to a semiconductor wafer, and a transmission pattern corresponding to the isolated line pattern.
  • a minimum transmittance part with the smallest transmittance, a slit-shaped maximum transmittance part that is formed outside the minimum transmittance part and has the largest transmittance, and is formed in the remaining area other than the minimum transmittance part and the maximum transmittance part Preparing a photomask having an intermediate transmittance portion between the minimum transmittance and the maximum transmittance, forming a resist film on the surface of the semiconductor wafer, and exposing the photomask. Arranging the semiconductor wafer on which the resist film is formed in the exposure apparatus, and transferring the mask pattern to the photo resist film applied to the semiconductor wafer by the exposing apparatus Exposure step.
  • the transmittance of the minimum transmittance part is 0 to 10%
  • the transmittance of the maximum transmittance part is 80 to 100%
  • the transmittance of the middle transmittance part is 10 to 80%. be able to.
  • a positive resist film can be used as the resist film.
  • the illumination system of the exposure apparatus may be modified illumination.
  • the isolated mask line pattern formed by the minimum transmittance portion has a width almost corresponding to the isolated line pattern transferred onto the wafer in wafer pattern conversion, and the maximum transmittance portion has a high light transmitted therethrough. It has the width to be the next diffraction light. Construct a repetitive mask pattern and minimize:
  • the mask line pattern formed by the parts has a width wider than the width of the line pattern transferred onto the semiconductor wafer in wafer pattern conversion.
  • the mask space pattern formed by the maximum transmittance portion has a width narrower than the space pattern transferred onto the semiconductor wafer in wafer pattern conversion.
  • the isolated mask space pattern formed by the maximum transmittance portion has a width smaller than the width of the isolated space pattern transferred onto the semiconductor wafer in wafer pattern conversion.
  • the photomask of the present invention has a mask line pattern and a mask space pattern corresponding to a line pattern and a space pattern transferred to a semiconductor wafer, and has a minimum transmittance portion corresponding to the mask line pattern and having the smallest transmittance. And a slit-shaped maximum transmittance part formed outside the minimum transmittance part and having the largest transmittance, and a minimum transmittance and maximum transmittance formed in the remaining area other than the minimum transmittance part and the maximum transmittance part And an intermediate transmittance portion having an intermediate transmittance.
  • the repetitive mask pattern may be formed by phase shift.
  • the minimum transmittance portion may be a halftone phase shift film.
  • the method for manufacturing a photomask according to the present invention includes the steps of forming a first metal film having a transmittance of a minimum transmittance portion on a photomask substrate; and forming a mask line pattern of the first metal film formed on the photomask. Removing a portion other than the portion corresponding to the above, forming a second metal film having a transmittance of an intermediate transmittance portion on the photomask substrate after the removal process is completed, and Forming a maximum transmittance portion by thinly removing a portion of the two metal films corresponding to the outside of the first metal film. A portion of the second metal film corresponding to the outside of the first metal film may be removed to form a maximum transmittance portion having a transmittance of 100%.
  • a semiconductor wafer is formed.
  • the edge portion of the pattern has a sharp rising light intensity distribution.
  • a line pattern such as a circuit and a wiring can be transferred onto a semiconductor wafer at a high resolution with a deep depth of focus.
  • an isolated line pattern transferred on a semiconductor wafer can be transferred with high resolution and a large depth of focus.
  • the relative intensity of exposure light capable of transferring an isolated line or space pattern and the relative intensity of exposure light capable of transferring a repetitive pattern can be set in a range of a large relative strength.
  • the degree of freedom in pattern dimensions when transferring a pattern having a pattern of isolated lines or spaces and a repeated pattern is increased, and the degree of freedom in pattern design can be improved.
  • FIG. 1 is a schematic structural view showing a reduced projection exposure apparatus used in an exposure process for manufacturing a semiconductor integrated circuit device.
  • FIG. 2a is a plan view schematically showing a design pattern transferred onto a wafer.
  • 2b is a plan view showing a photomask on which a mask pattern for transferring the design pattern shown in FIG. 2a is formed in the same size as the design pattern transferred to the wafer, and
  • FIG. 2c is FIG. 2b is a plan view showing the photomask shown in FIG. 2b divided into different transmittances
  • FIG. 3a is a photomask corresponding to a portion corresponding to line 3a-3a in FIG. 3b is a cross-sectional view showing an isolated line pattern portion of a wafer to be formed, and
  • FIG. 1 is a schematic structural view showing a reduced projection exposure apparatus used in an exposure process for manufacturing a semiconductor integrated circuit device.
  • FIG. 2a is a plan view schematically showing a design pattern transferred onto a wafer.
  • FIG. 3b is a photomask at a portion corresponding to line 3b-3b in FIG. 2b and a corresponding repetitive pattern portion of the wafer, that is, a line pattern.
  • space pattern and FIG. 3c is a cross-sectional view showing a portion corresponding to the 3c-3c line in FIG. 2b, and a corresponding photomask and an isolated space pattern portion of the wafer.
  • 4a is a cross-sectional view showing a conventionally known normal type photomask for transferring an isolated pattern corresponding to FIG. 3a
  • FIG. 4b is a conventionally known photomask for transferring a repetitive pattern corresponding to FIG. 3b.
  • FIG. 4c is a cross-sectional view showing a normal type photomask
  • FIG. 4c is a cross-sectional view showing a conventionally known normal type photomask for transferring an isolated space pattern corresponding to FIG. 3c.
  • FIG. 5a is a photomask of the present invention.
  • FIG. 5b is a characteristic diagram showing the intensity distribution of the diffracted light on the lens pupil plane when an isolated line pattern is exposed by using FIG.
  • Fig. 6a shows the intensity distribution of the diffracted light on the lens pupil plane when the isolated line pattern is exposed using the normal photomask shown in Fig. 4a.
  • Fig. 6b is a characteristic diagram showing the intensity distribution of diffracted light on the lens pupil plane when the pattern is repeatedly exposed using the normal photomask shown in Fig. 4b.
  • FIG. 7B is a conceptual diagram showing the light intensity distribution on the pupil plane and the light intensity distribution on the wafer of the light transmitted through the isolated mask line pattern using the photomask of the present invention.
  • Conceptual diagrams showing the light intensity distribution on the pupil plane and the light intensity distribution on the wafer of light transmitted through the repetitive mask pattern.
  • Figures 8a to 8d show the isolated line pattern transferred onto the wafer.
  • FIG. 9 is a conceptual diagram showing the light intensity on a wafer of light transmitted through a mask line pattern and a mask space pattern having mutually different transmittances for copying, and the combined light intensity.
  • FIG. 1 is a flowchart showing a manufacturing process for manufacturing a photomask.
  • FIG. 11c is a cross-sectional view showing a manufacturing process of a photomask according to another embodiment
  • FIG. 12 is a flowchart showing a manufacturing process of a semiconductor integrated circuit device
  • FIG. 13a is an example of a modified illumination
  • Fig. 13b is a conceptual diagram showing multipoint illumination as another example of deformed illumination
  • Fig. 13c is a conceptual diagram showing an image system by deformed illumination
  • Figs. Fig. 14b shows the light intensity distribution of an isolated line pattern on a wafer.
  • 15a and 15b are characteristic diagrams showing the light intensity distribution of the repetitive pattern on the wafer for the photomask of the present invention and a normal photomask.
  • 16a and 16b are characteristic diagrams showing the light intensity distribution of the isolated space pattern on the wafer for the photomask of the present invention and a normal photomask
  • FIG. 18 shows an isolated line pattern. Characteristic lines showing the relationship between the relative intensity distribution of transmitted light on the wafer and the line width dimension when the repetitive pattern is simultaneously transferred to the wafer for the photomask of the present invention and a normal photomask. It is. BEST MODE FOR CARRYING OUT THE INVENTION
  • the reduction projection exposure apparatus used in the exposure step is also called an i-line stepper, and has, for example, an adsorption table 11 that adsorbs and holds a semiconductor wafer 10 made of silicon single crystal or the like.
  • an exposure operation is performed by a step-and-repeat method.
  • the suction table 11 is an XY stage having an X-axis movement table 12a that moves in the horizontal direction and a Y-axis movement table 12b that moves the suction table 11 in the horizontal direction at a right angle to the X-axis movement table 12.
  • the suction table 11 is vertically movable by a Z-axis moving table 13.
  • a shirt 22 and a fly-eye lens 23 are arranged, and light passing through the fly-eye lens 23 is coherence factor by an aperture 24. That is, the partial coherency (high value) is adjusted, and the bandpass filter 25 excites illumination light other than the i-line.
  • the reticle, ie, the hot mask 26, is held by a mask holder 27, and the mask holder 27 can be finely adjusted in the Z-axis direction.
  • the area to be transferred to the semiconductor wafer 10 in the area of the photomask 26 is set by the mask blind 28.
  • Figure 2a shows the line patterns that make up the circuit, wiring, and bonding pad parts designed to be formed on the semiconductor wafer 10, the space patterns that are adjacent to each line pattern, and these lines.
  • Equation 1 shows a part of the surplus area other than the pattern of patterns and spaces.
  • This design pattern has a repetitive pattern 33 in which a linear pattern, that is, a line pattern 31 and a space pattern 32 are repeated adjacent to each other, and an L & S pattern is repeated.
  • One of the line patterns 31 in the return pattern 3 3 is elongated and becomes an isolated state, and the isolated line pattern pattern 3 4 is connected to the line pattern 31 and is designed to be larger than the linear pattern. For example, it has an isolated space pattern 36 sandwiched between large line patterns 35 corresponding to a bonding pad portion.
  • FIGS. 2b and 2c are diagrams showing a photomask 26 for transferring the design pattern corresponding to FIG. 2a, respectively. It has a mask line pattern, a mask space pattern, and an extra mask region corresponding to the regions.
  • the reduction projection exposure apparatus shown in FIG. 1 is a projection exposure apparatus having a reduction ratio of 5: 1
  • the photomask 26 used for this has a size five times as large as the design pattern.
  • the photomask 26 is illustrated as having the same size as the design pattern on the wafer for convenience of drawing. The same applies to the mask line pattern and mask space pattern of the photomask and the line pattern and space pattern transferred onto the wafer 10 as shown below.
  • the design pattern on the wafer and the mask pattern on the hot mask are shown as having the same size.
  • the photomask 26 is composed of a mask line pattern 41 corresponding to the line pattern 31 transferred to the wafer 10 and a linear mask space pattern 42 corresponding to the linear space pattern 32. These form a repetitive mask pattern 43. Further, an isolated mask line pattern 44 corresponding to the isolated line pattern 34 is formed on the hot mask 26, and a large mask line pattern 45 corresponding to the large pattern 35 and an isolated space pattern 36 are formed. An isolated mask space pattern 46 corresponding to the above is formed.
  • the mask line patterns 4 1 and 4 5, including the isolated mask line pattern 4 4, have a light transmittance of, for example, 0% and the minimum transmittance portion 51 having the smallest transmittance. Is shown in black in FIG. 2c.
  • the portion corresponding to the outside of each of the patterns 41, 44, and 45 becomes a slit and has a transmittance of, for example, 100%, and the maximum transmittance portion having the largest transmittance. 5 2, which are shown in white in FIG. 2c.
  • the extra area 47 of the photomask 26 corresponding to the extra area 37 of the wafer 10 has a transmittance intermediate between the minimum transmittance part 51 and the maximum transmittance part 52, for example, 50%.
  • the transmissivity is the intermediate transmittance portion 53, which is indicated by a dot in FIG. 2c.
  • Figure 3a shows the wafer 10 corresponding to the isolated line pattern 34 and the corresponding photo
  • FIG. 3B shows a portion of the wafer 10 corresponding to the portion of the repetitive pattern 33 and a portion of the photomask 26 corresponding thereto.
  • FIG. 3C shows the wafer 10 of the isolated space pattern 36 and the portion of the photomask 26 corresponding thereto.
  • a state in which a resist film 40 is formed on the surface of the wafer 10 is shown, and the hatched portions correspond to the line patterns 31, 34, and 35.
  • Corresponding, hatched parts are space patterns 3 2, 3 6 and extra area
  • the isolated mask line pattern of the photomask 26 is used to transfer the isolated line pattern 34 having a width of 0.4 ⁇ m onto the wafer 10.
  • 4 4 is formed by a minimum transmittance portion 51 having the same width as the wafer size in the width of the isolated line pattern 34, and outside the minimum transmittance portion 51, there is 0 in wafer conversion.
  • a maximum transmittance portion 52 having a width of 15 m is formed in a slit shape, and a portion of the extra region 47 outside this portion is an intermediate transmittance portion 53.
  • the boundary between the mask line patterns 41, 44 and 45 and the surplus area 47 has a minimum transmittance portion 51 corresponding to these line patterns.
  • the maximum transmittance portion 52 is formed in a slit shape outside the edge, and the width of the slit-shaped maximum transmittance portion 52 is the maximum transmittance portion shown in FIG. 3a. It is 0.15 m as in 5 2.
  • the portion outside the slit-shaped maximum transmittance portion 52, that is, the surplus region, is an intermediate transmittance portion 53.
  • a repeating pattern 33 in which a line pattern 31 having a width of 0.4 m and a linear space pattern 32 having the same width are repeated on the wafer 10 is formed.
  • the repetitive mask pattern 43 of the hot mask 26 has a width larger than the width of the linear line pattern 31, for example, a minimum transmittance portion 51 set to 0.54 m. It is formed by repeating a width smaller than the width of the space pattern 32 in terms of a wafer, for example, a maximum transmittance portion 52 of 0.26 m.
  • the isolated mask space pattern of the photomask 26 is used to transfer a 0.4 m wide lined isolated space pattern 36 onto the wafer 10.
  • FIGS. 4A to 4C are diagrams showing, as a related art, a conventionally known ordinary photomask for transferring the same pattern as described above to a wafer.
  • the normal photomask 26a has a narrow opaque mask line pattern 44a to transfer the isolated line pattern 34a to the ueno, 10a, and the other parts are transparent. Has become.
  • the normal photomask 26a is the same as the pattern 31a in order to transfer the repetition pattern 33a of the line pattern 31a and the space pattern 32a on the wafer 10a.
  • FIG. 5a shows an isolated mask line pattern in which the edge of the isolated line pattern 34 becomes the minimum transmittance portion 51 in order to transfer the isolated line pattern 34 onto the wafer 10 as shown in FIG. 3a.
  • the maximum transmittance portion 52 with a narrow width is formed in the form of a slit outside the isolated line pattern 34, almost corresponding to the edge of 4 4, and the surplus region 47 is formed by the intermediate transmittance portion 53.
  • FIG. 7 is a characteristic diagram showing an intensity distribution of diffracted light on a pupil plane 20 in a reduction projection exposure apparatus when a photomask 26 is used.
  • the mask line patterns 41, 44, and 45, which are used to transfer the other line patterns 31, 35, including this isolated line pattern 34, are also used.
  • a narrow minimum transmittance portion 51 having a narrow width, and has the same intensity distribution of diffracted light.
  • the intensity of the diffracted light at the pupil plane 20 is the square of the absolute value of the light amplitude.
  • FIG. 5B has a repetitive mask pattern 43 of a minimum transmittance portion 51 and a maximum transmittance portion 52 in order to transfer the repetition pattern 33 onto the wafer 10 as shown in FIG. 3B.
  • FIG. 9 is a characteristic diagram showing an intensity distribution of diffracted light on a pupil plane 20 in a reduction projection exposure apparatus when a hot mask 26 is used.
  • FIG. 6A is a characteristic diagram showing the intensity distribution of the diffracted light on the pupil plane 20 when the hot mask 26a having the normal isolated mask line pattern 44A shown in FIG. 4A is used.
  • Figure 6b shows a photo with the normal repeating pattern 43a shown in Figure 4b.
  • FIG. 14 is a characteristic diagram showing a similar intensity distribution of diffracted light when a mask 26a is used.
  • the pupil generated by the isolated mask line pattern 44 is obtained.
  • the intensity distribution of the diffracted light on the surface 20 spreads to a large angle, and the higher-order light including the ⁇ -order light becomes stronger compared to the normal photomask 26a.
  • the repetitive mask pattern 43 is transferred using the photomask 26, diffraction at the pupil plane caused by the repetitive mask pattern 43 is generated. In the light intensity distribution, the primary soil light is weaker than the conventional photomask 26a.
  • Fig. 7a shows the intensity distribution of diffracted light on the pupil plane when an isolated line pattern is transferred using a photomask 26 having three types of transmittances with different transmittances.
  • the maximum transmittance portion 52 having a narrow width is formed outside the isolated mask pattern 44 formed by the minimum transmittance portion 51, and the extra region 47 is formed as an intermediate transmittance portion 53.
  • the high-intensity slit light transmitted through the minimum transmittance section 51 spreads over a large ft degree range, and the higher-order diffraction light on the pupil plane becomes strong.
  • the distribution of the light intensity in the portion corresponding to the edge of the isolated line pattern 34 on the wafer 10 sharply rises and becomes close to a rectangular wave. This is the same at the boundary between the line patterns 3 and 35 and the extra area 37.
  • FIG. 7B is a diagram showing the intensity distribution of the diffracted light on the pupil plane and the light intensity distribution on the wafer 10 when the repetitive pattern 33 is transferred using the photomask 26.
  • FIG. 8 is a diagram showing a light intensity distribution of an isolated line pattern on the wafer 10 when an isolated pattern is transferred using the photomask 26.
  • FIG. 8A shows that the light intensity on the wafer 10 due to the light transmitted through the minimum transmittance portion 51 having a transmittance of 0% is zero, and there is no light intensity distribution.
  • FIG. 8B shows that the light intensity distribution on the wafer 10 due to the light transmitted through the intermediate transmittance portion 53 having a transmittance of 50% becomes concave.
  • FIG. 8C shows that the light intensity distribution on the wafer 10 due to the light transmitted through the maximum transmittance portion 52 having a transmittance of 100% has two peaks.
  • FIG. 8d is a diagram showing the intensity distribution of light irradiated on the wafer 10 by combining light transmitted through portions having different transmittances.
  • the combined light has an intensity having a sharp rising waveform.
  • the distribution becomes strong and the contrast of intensity is emphasized.
  • it is possible to transfer a line pattern and a space pattern such as a circuit and a wiring on the semiconductor wafer 10 with high resolution and a large depth of focus.
  • the transmittance of the minimum transmittance portion 51 is set to 0%. However, an arbitrary transmittance can be set within a range of 0 to 10%. Although the transmittance of the maximum transmittance portion 52 is set to 100%, any transmittance can be set within the range of 80 to 100%. Although the transmittance of the intermediate transmittance portion 53 is set to 50%, an arbitrary transmittance can be set within a range of 10 to 80%.
  • the photomask 26 is configured by a mask pattern having three types of regions having mutually different transmittances. However, a mask pattern having more than three types of transmittances is provided. The hot mask 26 may be constituted by the components. The values of these transmittances and the types of the transmittances are set by the width of the mask line pattern and the mask space pattern according to the dimensions of the line pattern and the space pattern transferred to the wafer 10.
  • the minimum transmittance portion 51 may be a halftone phase shift film, and the repetitive mask pattern 43 may be a Levenson type phase shift film.
  • FIG. 9 is a diagram showing a manufacturing process for manufacturing the photomask 26 of the present invention.
  • the surface of a synthetic quartz glass plate is polished and washed to create a transparent mask substrate (D).
  • a metal opaque film such as chromium (Cr) is deposited on the entire surface of the main surface of the mask substrate by sputtering or the like to form the minimum transmittance portion 51 (step S 2).
  • an electron-sensitive resist film is spin-coated on the entire surface of the metal opaque film.
  • step S3 After coating (step S 3) by a liquid method, the resist film is exposed by, for example, a direct drawing method using an electron beam exposure apparatus, and the minimum transmittance portion 51 is applied to the electron-sensitive resist film on the metal film.
  • the transferred pattern is transferred (step S4). Thereafter, if the electro-sensitive resist film is a negative type, the unexposed portion is removed with a predetermined developing solution (Step S5).
  • FIG. 10a shows a metal opaque film as a minimum transmittance portion 51 having a transmittance of 0% formed on a mask substrate 260.
  • Step S8 a metal thin film such as chromium is deposited on the entire main surface of the mask substrate and the upper surface of the metal opaque film by sputtering or the like.
  • FIG. IOb shows a state in which a metal thin film is deposited to form an intermediate transmittance portion 53.
  • the transmittance can be set to an arbitrary value by adjusting the thickness of the metal thin film, and the thickness of the metal opaque film as the minimum transmittance portion 51 and the thickness of the metal thin film as the intermediate transmittance portion 53 are set.
  • the transmittance of the minimum transmittance portion 51 can be set to almost 0% even when chromium is used.
  • a metal film for forming the minimum transmittance portion 51 and the intermediate transmittance portion 53 besides chromium, other metals such as molybdenum (Mo) or titanium (Ti) are used. You may do it.
  • the resist is preferably a positive type. In this way, as shown in FIG. 10c, a maximum transmittance portion 52 having a transmittance of 100% is formed, and the manufacture of the photomask 26 is completed.
  • a halftone phase shift film is formed as the minimum transmittance portion 51.
  • a photomask having such a phase shift film can be manufactured in the same manner as the process shown in FIG. 9 by depositing a halftone phase shift film in step S2 in FIG. It can be manufactured by the process of.
  • FIG. 11 shows an outline of a manufacturing process in that case.
  • a Levenson-type phase shift pattern having a phase shift portion in a portion corresponding to every other mask space pattern 42 of the repetitive mask patterns 43 is formed.
  • a metal thin film is deposited on the entire upper surface of the main surface of the mask substrate 260 in the same manner as shown in FIG. 10b to form an intermediate transmittance portion 53.
  • FIG. 11b a metal thin film is deposited on the entire upper surface of the main surface of the mask substrate 260 in the same manner as shown in FIG. 10b to form an intermediate transmittance portion 53.
  • the photo-etching process includes a photolithography process for forming a resist film pattern on the wafer 10, an etching process for etching an insulating film using the resist film pattern as a mask, and a resist process for removing the resist film pattern. Film removal process.
  • a resist coating pretreatment is performed in order to remove the K substances from the wafer 0 and to enhance the adhesion of the resist film pattern after development to the anode 10 (step S). twenty one ) .
  • a resist film having a predetermined thickness is uniformly applied to the wafer 10 on which the pretreatment is completed by a spin coating method (step S22).
  • a resist material a positive type ultraviolet resist is used because high resolution can be obtained.
  • the wafer 10 is baked using a hot plate to volatilize the residual solvent contained in the resist film immediately after coating and stabilize the photochemical reaction at the time of exposure (step S23). ).
  • the wafer 10 on which the resist film has been formed in this manner is placed on the suction table 11 of the reduction projection exposure apparatus shown in FIG.
  • step S24 and formed as described above.
  • the prepared and prepared photomask 26 is placed on a mask holder 27 of an exposure apparatus (step 25). With the wafer 10 and the photomask 26 correctly positioned at the specified positions, the mask is exposed to ultraviolet light (i-line) with a wavelength ⁇ of 0.365 m from the light source 16 for a certain period of time. The pattern is transferred onto the wafer 10 (step S26). The exposure time is set longer when the photomask 26 is used than when the normal photomask 26a is used.
  • a step & repeat method is used.
  • movement and stop on the stage side are repeated, and scanning is performed during stop to draw.
  • the exposure method may be a step & scan method.
  • slit exposure is performed by synchronously scanning a reticle and a wafer at a ratio of 4: 1.
  • a step operation is performed on the next exposure scan area, and the entire surface of the wafer is exposed by repeating the scan and the steps.
  • a developing solution is dropped in a developing step S27 to form a resist film pattern.
  • the etching step (S28) the insulating film is etched using the resist film pattern as a mask.
  • FIG. 13c shows a reduced projection exposure apparatus of a modified illumination system.
  • the deformed illumination method is also called an oblique incident illumination method.
  • a ring-shaped or ring-shaped as shown in Figure 13a Illumination and multipoint illumination as shown in Fig. 13b.
  • the mask pattern is reproduced by interference of two light beams of zero-order light and minus primary light or zero-order light and plus primary light among the light beams diffracted by the photomask 26.
  • FIG. 14 the solid line shows the isolated mask line pattern 4 shown in FIG. 3 a under the exposure conditions of wavelength ⁇ 3 65 // m, ⁇ value 0.55, and ⁇ ⁇ 0.52.
  • FIG. 2 is a characteristic diagram showing a distribution of light intensity on a wafer 10 when a photomask 26 having 4 is attached to the reduction projection exposure apparatus shown in FIG.
  • the width of the minimum transmittance portion 51 in the photomask 26 was set to 0.4 m, which is the same as the width of the isolated pattern 34, and the width of the maximum transmittance portion 52 was set to 0.15 m.
  • FIG. 14 the solid line shows the isolated mask line pattern 4 shown in FIG. 3 a under the exposure conditions of wavelength ⁇ 3 65 // m, ⁇ value 0.55, and ⁇ ⁇ 0.52.
  • FIG. 2 is a characteristic diagram showing a distribution of light intensity on a wafer 10 when a photomask 26 having 4 is attached to the reduction projection exposure apparatus shown in FIG.
  • FIG. 9 is a characteristic diagram showing a distribution of light intensity, and the line width of the mask putter in the photomask 26a was 0.25 m.
  • FIG. 14a shows the light intensity distribution at the best focus position on the wafer 10
  • FIG. 14b shows the light intensity distribution at the defocus position shifted by 0.6 m from the best focus position.
  • the intensity distribution corresponding to the pattern edge of the isolated line pattern 34 on the wafer 10 becomes sharp, and
  • the positive resist film which becomes soluble in the developer is removed, and the portion corresponding to the isolated line pattern 34 of 0.4 im is removed.
  • the resist film remains as a line pattern.
  • FIG. 15 the solid line shows the pattern on the wafer 10 when the wafer 10 is exposed by the photomask 26 having the repetitive mask pattern 43 shown in FIG.
  • FIG. 4 is a characteristic diagram illustrating a distribution of light intensity.
  • the width of the maximum transmittance portion 52 in the photomask 26 was 0.26 m.
  • the dashed line in FIG. 15 indicates the light intensity distribution when the wafer 10a is exposed using the normal photomask 26a having the repetitive mask pattern shown in FIG. 4b under the same exposure conditions.
  • the width of each of the line pattern and the space pattern on the photomask 26a is 0.4 ⁇ m in the same manner as the line pattern 31a and the space pattern 32a on a wafer basis. It is.
  • the solid line is a characteristic line showing the light intensity distribution when the wafer 10 is exposed by the photomask 26 having the isolated mask space pattern 46 shown in FIG. 3c under the same exposure conditions.
  • the width of the maximum transmittance portion 52 is set to 0.28 m, which is smaller than the width of the isolated space pattern 36.
  • the dashed line in FIG. 16 indicates the light intensity distribution when the wafer 10a is exposed under the same exposure conditions using a normal photomask 26a having an isolated space pattern shown in FIG. 4c.
  • FIG. 17 shows a case where an isolated line pattern and a repetitive pattern are transferred onto a wafer 10 using the photomask 26 of the present invention and a case where a wafer 10a is printed using a normal photomask 26a.
  • FIG. 7 is a characteristic diagram showing relative intensities of irradiation light on a wafer when a similar pattern is transferred.
  • the range R in which the relative intensity of the isolated pattern transferred to the wafer by the photomask of the present invention and the relative intensity of the repetitive pattern overlap is the overlap range Ra when a normal photomask 26a is used. It turns out that it became large compared with.
  • the boundary between the part of the resist film that is removed by the developer and the part that is not removed is set by the threshold value of the relative strength according to the characteristics of the resist material. Not only does the freedom to select the resist material to be added increase, but also the degree of freedom in pattern design improves.
  • FIG. 18 is a characteristic diagram obtained by measuring the relationship between the line width of the repetitive pattern and the isolated line pattern and the relative intensity of the exposure light for the mask pattern of the present invention and a normal mask pattern.
  • the range of line width that can be set for each pattern is narrower than La for a normal photomask. L is more than doubled, and the degree of freedom in pattern design is greatly improved.
  • the line width is set to 0.7 m or more.
  • the lines in the repeating pattern will contact each other, and if the line width is set to 0.05 m or less, the line pattern will disappear.
  • the invention made by the inventor has been specifically described based on the embodiment. ⁇ The invention is not limited to the above embodiment, and can be variously changed without departing from the gist of the invention. Needless to say.
  • the intermediate transmittance portion 53 may be formed by a dot pattern, or may be formed by a dot step pattern having a phase difference.
  • the transfer can be performed at an arbitrary reduction ratio such as a force of 10: 1 when the reduction ratio of the reduction projection exposure apparatus is set to 5: 1, and it is also possible to transfer at the same magnification. .
  • the method of manufacturing a semiconductor integrated circuit device according to the present invention is suitable for use in the manufacture of various types of semiconductor integrated circuit devices, such as memories such as DRAM and various super LSIs.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Abstract

Le procédé de fabrication d'un dispositif à circuit intégré à semiconducteur comprend une étape d'exposition de transfert d'une configuration de masque qui est formée sur un photomasque (26) et comprend une configuration de ligne de masque et une configuration d'espace de masque sur la surface d'une tranche à semiconducteur (10). Le photomasque (26) possède une section de transmittance minimum (51) qui est formée de manière à correspondre à la configuration de ligne transférée sur la tranche (10) et possède la transmittance minimum, une section de transmittance maximum en forme de fente (52) qui est formée à l'extérieur de la section (51) et qui possède la transmittance maximum, et une section de transmittance intermédiaire (53) qui est formée dans la zone (47) différente des sections (51 et 52) et possède une transmittance intermédiaire se situant entre les transmittances minimum et maximum. La lumière à laquelle la surface de la tranche (10) est exposée possède une distribution de forte intensité au niveau du bord de la configuration de ligne, ce qui permet d'améliorer la résolution de cette dernière.
PCT/JP1996/001513 1996-06-05 1996-06-05 Procede de fabrication d'un dispositif a circuit integre a semiconducteur, photomasque et procedes de fabrication d'un photomasque WO1997046914A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/JP1996/001513 WO1997046914A1 (fr) 1996-06-05 1996-06-05 Procede de fabrication d'un dispositif a circuit integre a semiconducteur, photomasque et procedes de fabrication d'un photomasque

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP1996/001513 WO1997046914A1 (fr) 1996-06-05 1996-06-05 Procede de fabrication d'un dispositif a circuit integre a semiconducteur, photomasque et procedes de fabrication d'un photomasque

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WO1997046914A1 true WO1997046914A1 (fr) 1997-12-11

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05198497A (ja) * 1992-01-21 1993-08-06 Fujitsu Ltd 半導体装置の製造方法
JPH05297565A (ja) * 1992-04-22 1993-11-12 Toshiba Corp 投影露光用基板の製造方法とこの基板を用いたパターン形成方法
JPH06177011A (ja) * 1992-09-03 1994-06-24 Samsung Electron Co Ltd 投影露光方法、これに使用される投影露光装置およびマスク

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05198497A (ja) * 1992-01-21 1993-08-06 Fujitsu Ltd 半導体装置の製造方法
JPH05297565A (ja) * 1992-04-22 1993-11-12 Toshiba Corp 投影露光用基板の製造方法とこの基板を用いたパターン形成方法
JPH06177011A (ja) * 1992-09-03 1994-06-24 Samsung Electron Co Ltd 投影露光方法、これに使用される投影露光装置およびマスク

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