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Showing papers on "Phase-shift mask published in 1993"


Patent
15 Nov 1993
TL;DR: In this article, the phase shift mask has high quality and the process for production thereof by decreasing processes at the time of producing the phase shifter mask and to provide the exposure method using the Phase Shift Mask.
Abstract: PURPOSE:To provide the phase shift mask having high quality and the process for production thereof by decreasing processes at the time of producing the phase shift mask and to provide the exposure method using the phase shift mask CONSTITUTION:A second light transparent part 4 of the phase shift mask 200 is composed of molybdenum silicide oxynitride or molybdenum silicide oxide 4, of which the phase difference attains 180 deg and transmittance is 5 to 40% A molybdenum silicide oxynitricle film or molybdenum silicide oxide film is formed by using a sputtering method in the production stage for the second light transparent part 4 As a result, the second light transparent part is formed by using the conventional sputtering device and since the etching stage of the phase shifter parts is just once, the probability of generating defects and errors in the production stage is lowered

78 citations


Journal ArticleDOI
TL;DR: The potential, working principles, and approaches in phase shifting masks for optical lithography are discussed in this article, and the tradeoffs of each approach, and fabrication, inspection, repair, and tolerances are considered.
Abstract: The potential, working principles, and approaches in phase shifting masks for optical lithography are discussed. The tradeoffs of each approach, and fabrication, inspection, repair, and tolerances are considered. It is feasible to use the phase shifting technology to improve optical lithography to 0.18- mu m feature size with k/sub 1/=0.35, lambda =248 nm, and NA=0.5. Further resolution improvements are still possible, but much development is required for making phase shifting masks a manufacturing reality. >

72 citations


Journal ArticleDOI
TL;DR: A novel algorithm for successively assigning phases to apertures which are arranged in descending order of pattern design modification difficulty is proposed, to make pattern modification easier.
Abstract: A systematic approach to assigning aperture phases for the alternate-type phase-shift mask is proposed. Since the alternate-type phase-shift mask requires a 180° phase difference between adjacent apertures, there is the possibility that phase conflicts will arise, thus requiring pattern design modification. As a way to make pattern modification easier, this paper proposes a novel algorithm for successively assigning phases to apertures which are arranged in descending order of pattern design modification difficulty. Relative difficulty can be input by the pattern designer and/or calculated by the system from the pattern features. The system's successive shifter arrangement and phase conflict display is demonstrated on a test pattern.

72 citations


Patent
31 Aug 1993
TL;DR: In this paper, a translucent phase shift mask and a light-shielding film are formed on a transparent substrate by etching, and the projected part of the phase shift film is formed to project in the horizontal direction by length Z from the edge of the light shielding film.
Abstract: PURPOSE: To surely shield the peripheral part of an effective region of a halftone phase shift mask from light by a simple method without using a complicated light-shielding band which is conventionally used. CONSTITUTION: A translucent phase shift film 2a of a desired pattern and a light-shielding film 11b of almost the same pattern are formed on a transparent substrate 1 by etching. Substrate 1 consists of the effective region 8 of an area (a×b) where the desired pattern is formed and the peripheral part 9 surrounding the effective region. The light-shielding film 11b is deposited on both of the phase shift film 2a in the peripheral part 9 and the phase shift film 2a in the effective region 8. However, the edge of the phase shift film 2a is formed to project in the horizontal direction by length Z from the edge of the light- shielding film 11b. With this projected part, the phase of exposure light is inverted between the light-shielding part and the light-transmitting part which interpose the projected part between them so that these parts can be clearly separated from each other.

50 citations


Journal ArticleDOI
TL;DR: The conjugate twin shifter method for alternating phase shift method provides the flexibility for mask shifter layout, and is applied for both isolated and periodic shifter arrays in conventional i−line positive resist processes.
Abstract: The conjugate twin‐shifter method for alternating phase‐shift method provides the flexibility for mask shifter layout, and is applied for both isolated and periodic shifter arrays in conventional i‐line positive resist processes. A new mask structure simplifies shifter pattern delineation and reduces the effects of phase defects. The detail of intermediate phase interference has been analyzed by applying the two‐dimensional shifter array as the phase defect. The results of this analysis provides the optimum repair element array for the new repair method of phase defects. Then the effectiveness of this simple repair method is examined in the i‐line process by using the test arrays that delineated in the XeF2 assisted focused ion beam process.

49 citations


Journal ArticleDOI
TL;DR: In this article, the optical properties of a plasma-deposited amorphous carbon film were investigated in the ultraviolet (365 nm) and deep ultraviolet range (248 nm) for single layer attenuated phase shift masks for potential application in 0.25 μm lithography at 365 and 248 nm.
Abstract: The optical properties of a plasma‐deposited amorphous‐carbon film have been investigated in the ultraviolet (365 nm) and deep ultraviolet range (248 nm). By varying process conditions, the optical transmission through the films was tuned from 4% to 20% at 365 nm and from 3% to 9% at 248 nm. This tuneability was related to the hydrogen content of the film as affected by the process parameters. The index of refraction n measured by spectroscopic ellipsometry is ∼2 at the wavelengths used. These optical properties make this film attractive for use in single layer attenuated phase‐shift masks for potential application in 0.25 μm lithography at 365 and 248 nm.

34 citations


Proceedings ArticleDOI
Patrick M. Troccolo1, Donald K. Cohen, Nelson N. Tam1, Giang T. Dao1, Qi-De Qian1 
04 Aug 1993
TL;DR: In this paper, a method of interferometrically evaluating a phase shift mask is proposed, assuming that a good optical surface is maintained on the unetched regions of the mask.
Abstract: Using etched quartz as a phase shifter for i-line phase shift masks requires an etched depth of 385 nm referenced from the quartz surface. Recent work shows a direct relationship of focus offset as a function of the phase angle as it deviates from 180 degree(s). Knowing the etched depth and phase in transmission becomes critical to the production and verification of these masks. A method of interferometrically evaluating a phase shift mask is proposed. The method calculates the phase shift from the surface profile of the etched shifter assuming that a good optical surface is maintained on the unetched regions. This surface measurement method possesses high spatial resolution at the expense of only knowing the amount of phase shift from the profile of the etched quartz shifter. Correlations between this method and mechanical stylus measurements establish the validity and advantages of this measurement technique.

27 citations


Patent
03 Dec 1993
TL;DR: In this paper, the authors proposed an exposure half-tone type phase shift mask capable of preventing the fluctuation of the physical properties of a translucent film due to the irradiation of exposure light, and contributing to the improvement of pattern transfer accuracy.
Abstract: PURPOSE:To provide an exposure half-tone type phase shift mask capable of preventing the fluctuation of the physical properties of a translucent film due to the irradiation of exposure light, and contributing to the improvement of pattern transfer accuracy. CONSTITUTION:Regarding the exposure half-tone type phase shift mask made of a SiN translucent film 102 formed on a transparent substrate to a desired pattern, the features are that light having wavelength included in the absorption band of the film 102 for exposure wavelength is radiated from the side of the substrate 101 to the film 102, thereby forming a stabilizing layer 103 at a boundary between the substrate 101 and the film 102 to prevent the physical property fluctuation of the film 102 due to the exposure light being radiated.

23 citations


Proceedings ArticleDOI
05 Dec 1993
TL;DR: In this article, an attenuated phase-shifting mask with a single-layer absorptive shifter with MoSiO or MoSiON films has been developed, which satisfies the condition both the 180-degree phase shift and the transmittance between 5 and 20%
Abstract: Attenuated phase-shifting mask with a single-layer absorptive shifter with MoSiO or MoSiON films has been developed These films satisfies the condition both the 180-degree phase shift and the transmittance between 5 and 20% Conventional mask processes, such as etching, cleaning, defect inspection and defect repair, can be used for the fabrication Defect-free masks for hole layers of 64 M-bit DRAM have been obtained Using this mask, the focus depth of 035-/spl mu/m hole is improved from 06 /spl mu/m to 15 /spl mu/m >

23 citations


Patent
22 Dec 1993
TL;DR: The phase shift mask blank of halftone type has at least one layer of a thin film including silicon, nitrogen and/or oxygen formed on a transparent substrate, and is used for exposure light with a center wavelength not longer than 248 nm.
Abstract: PROBLEM TO BE SOLVED: To adjust the internal stress of a semitransparent film a suitable range in state where the resistance to acid, the resistance to alkali and the resistance to impinging excimer laser of the semitransparent film formed in a phase shift mask blank or the like are improved. SOLUTION: The phase shift mask blank of halftone type has the semitransparent film with at least one layer of a thin film including silicon, nitrogen and/or oxygen formed on a transparent substrate, and is used for exposure light with a center wavelength not longer than 248 nm. The surface of the semitransparent film is precisely formed so that the surface roughness is not more than 0.3 nm in Ra. COPYRIGHT: (C)2002,JPO

21 citations


Proceedings ArticleDOI
08 Aug 1993
TL;DR: The main advantage of this object-oriented approach over the previous pixel-based solution is that it results in substantially larger assisting phase shift features, and is therefore easier to fabricate.
Abstract: We propose a new approach to systematic phase shift mask design. In doing so, we constrain the complexity of the mask at a pre-specified level by limiting the number of `features' on the mask. We then optimize the location, size, and phase of the features so as to achieve a desired intensity pattern on the wafer. The main advantage of this object-oriented approach over our previous pixel-based solution is that it results in substantially larger assisting phase shift features, and is therefore easier to fabricate. Our approach can also be used to design masks with proper bias and/or extension of the depth of focus. We show examples of contact hole, bright line, and chromeless line-space mask designs.

Patent
26 Mar 1993
TL;DR: In this article, a halftone type phase shift mask is proposed to prevent the generation of a defect of exposure based on a deviation between the light passage region of the apertures of a stepper and the transfer region of a phase shift masks which is a reticule.
Abstract: PURPOSE: To provide the halftone type phase shift mask capable of preventing the generation of a defect of exposure based on a deviation between the light passage region of the apertures of a stepper and the transfer region of a phase shift mask which is a reticule even if there is some deviation therebetween in the case of use of this phase shift mask as the reticule of the stepper. CONSTITUTION: This halftone type phase shift mask 1 is formed by forming a light translucent film 5 which shifts the phase of the light passing simultaneously with the passage of exposing light of the intensity of not substantially contributing to exposure over the entire surface of a transparent substrate 2, removing a part of the light translucent film 5 in the central part of the magnetic substrate 2 to form a mask pattern constituted of a light transparent part 6 and a translucent part 7 and varying the phase of the light passed the light translucent part 7 and the phase of the light passed the light transparent part 6 in such a manner that the light rays past the part near the boundary of the light transparent part and the light translucent part negate each other, thereby making it possible to well maintain the contrast in the boundary part. A light shielding part 8 having a prescribed or larger width is formed,in the non-transfer region adjacent to the boundary between the mask pattern transfer region 1 and non-transfer region on the light translucent film 5 made to remain on the outer periphery on the transparent substrate 2. COPYRIGHT: (C)1994,JPO

Patent
Yoshihiko Okamoto1
06 Dec 1993
TL;DR: A phase shift reducing projection exposure method for making it easy to make the pattern data of a phase shift mask capable of improving the focal depth of a transfer exposure plane and the resolution of a pattern was proposed in this paper.
Abstract: A phase shift reducing projection exposure method for making it easy to make the pattern data of a phase shift mask capable of improving the focal depth of a transfer exposure plane and the resolution of a pattern. The exposure method comprises: a first enlarging step of making the data of a primary transparent pattern by enlarging the width of repeating patterns to a predetermined extent under a process condition without changing the relative position coordinates of the repeating patterns when the pattern data on the phase shift mask are to be made; and a second enlarging step of making the data of an auxiliary transparent pattern by enlarging the width of the primary transparent pattern obtained in the data status by the first enlarging step to a predetermined extent on the basis of the characteristic conditions of a reducing projection exposure optical system, and subsequently by eliminating the data of the primary transparent pattern from the data of the enlarged primary transparent pattern.

Patent
31 Aug 1993
TL;DR: In this paper, an exposure mask and an exposure method are provided, which can suppress adverse effects of interference edge patterns (sub-shifters) located around a central pattern, and the exposure mask has central patterns and edge patterns arranged around each central pattern.
Abstract: An exposure mask and an exposure method are provided, which can suppress adverse effects of interference edge patterns (sub-shifters) located around a central pattern. The exposure mask has central patterns and edge patterns arranged around each central pattern. The mutual interference of edge patterns is reduced by providing an angle or a phase difference between vicinity edge patterns, or providing a single edge pattern to reduce the light transmission.

Patent
30 Nov 1993
TL;DR: In this paper, a phase shift mask of a chromium-less system is used to enable the transfer of desired patterns at desired pattern widths and decreased stages with phase shift masks.
Abstract: PURPOSE: To enable the transfer of desired patterns at desired pattern widths and decreased stages with a phase shift mask of a chromium-less system. CONSTITUTION: At least a part of the edges of phase shifters 3 consisting of a transparent material formed on a transparent substrate 1 are provided with dummy pattern edges 4 formed of a part of the phase shifters 3 so as to exist along the edges. The patterns in the edge parts of the phase shifters 3 are erased or the pattern width is made finer by changing the intervals of the edges of the dummy patterns 4 and the phaseg shifters, by which the exposing stage is simplified and the degree of freedom of pattern formation is enhanced. COPYRIGHT: (C)1995,JPO

Patent
31 Mar 1993
TL;DR: In this article, a light-shield film pattern and a phase shifter are formed on a transparent substrate, and an applied oxide film is used as the phase shift mask, where the phase shifters defect is supposed to be a bump defect.
Abstract: A light-shield film pattern and a phase shifter are formed on a transparent substrate. An applied oxide film is used as the phase shifter. On this phase shift mask, a phase shifter defect is present. On the phase shift mask containing the phase shifter defect, a silicon-containing resist is applied. At this time, the film thickness of the resist is 50 nm in the flat part. Herein, the phase shifter defect is supposed to be a bump defect. When the resist is formed in a film thickness of 50 nm, the phase difference of the light entering through the film thickness is about 30 degrees. This resist is exposed with electron beam in a region including the periphery of the defect. After electron beam exposure, it is developed. Since the silicon-containing resist is a negative resist, only the region irradiated with electron beam is left over after development. Since the resist has a mild slope, if exposed using this phase shift mask, the bump defect will not be projected. Thus, when the both sides of the bump defect are dull, if the defect height is more than the height of providing the light with a phase difference of 180 degrees, it will not be projected. When the both sides of the bump defect are moderate, the incident light also changes moderately in phase. In this case, the pattern is not projected.

Patent
30 Aug 1993
TL;DR: In this paper, the shifter material of auxiliary patterns 2 of the phase shift mask including main pattern 1 and auxiliary pattern 2 is formed as a material having controlled light transmittance, by which the resolution of pattern forming regions is improved.
Abstract: PURPOSE:To provide a phase shift mask with which a wide production allowance is taken CONSTITUTION:The shifter material of auxiliary patterns 2 of the phase shift mask including main patterns 1 and the auxiliary patterns 2 is formed as a material having controlled light transmittance The light peak intensity in the sufficient main patterns and secondary light peak intensity of the regulated value or below are obtd by the auxiliary patterns 2 of a large width, by which the resolution of pattern forming regions is improved The large production allowance of the mask is taken by adopting the auxiliary patterns 2 of the large width The production stages for semi-light shielding films are omitted if this phase shift mask is applied to a halftone phase shift mask

Patent
08 Oct 1993
TL;DR: In this article, a method of forming a pattern using a phase shift mask which comprises applying at least first and second exposures is presented, where at least one exposure is conducted by using the phase shifting mask and at least the other exposure is performed for compensating the amount of light at a phase shifting boundary of the mask, the pattern having an interpattern distance on a substrate of less than 2.4×λ/NA.
Abstract: A method of forming a pattern using a phase shift mask which comprises applying at least first and second exposures. At least one exposure is conducted by using a phase shifting mask and at least the other exposure is conducted for compensating the amount of light at a phase shifting boundary of the phase shifting mask, the pattern having an inter-pattern distance on a substrate of less than 2.4×λ/NA. The method of the present invention is applicable also to the formation of a pattern to which the existing phase shifting technique can not be applied, as well as to a pattern in which sub-patterns as the phase shifting portions can not be provided, whereby a pattern at a high resolution power can be obtained irrespective of the pattern shape.

Patent
29 Jan 1993
TL;DR: In this article, a phase shift mask provided with prescribed correction patterns 101b at the ends of a mask pattern region of a specified mode or in the boundary parts of the mask pattern regions of plural modes is used to expose diversified and fine patterns in the process for production of the semiconductor device or semiconductor integrated circuit device.
Abstract: PURPOSE:To provide the reduction stepping method which allows exposing of diversified and fine patterns in the process for production of the semiconductor device or semiconductor integrated circuit device. CONSTITUTION:This method consists in executing reduction stepping by using a phase shift mask provided with prescribed correction patterns 101b at the ends of a mask pattern region of a specified mode or in the boundary parts of the mask pattern regions of plural modes. Since an end effect, etc., are offset by the correction patterns, the exposing of the diversified and fine patterns is executed.

Proceedings ArticleDOI
08 Aug 1993
TL;DR: In this paper, Narrow poly lines were defined using the edge of a shifter rectangle with superimposed chrome lines of variable width to produce a range of linewidths.
Abstract: N-channel field effect transistors (FETs) with poly linewidths as small as 170 nm have been fabricated with phase shift mask (PSM) lithography using a 0.45 NA I-line stepper. Narrow poly lines were defined using the edge of a (pi) shifter rectangle with superimposed chrome lines of variable width to produce a range of linewidths. Using a chrome-less phase edge, resist linewidths of 240 nm were obtained at nominal exposure, while + 25% overexposure yielded linewidths of 190 nm. Excellent linewidth control was obtained on the device wafers with 3 (sigma) variation of roughly 20 nm for the resist lines. The use of a top anti-reflector (TAR) process improved linewidth control by approximately 35% relative to a normal single layer resist process. Linewidths were also measured after poly etch and, in the final devices, Leff was measured by electrical testing. Devices fabricated using PSM showed significant improvement in lithographic process latitude over control devices fabricated using conventional chrome masks.

Patent
05 Mar 1993
TL;DR: In this article, the phase shift mask is used for an exposure device using i rays and KrF excimer laser as light sources at the time of using the mask using a silicon oxide film as a phase shift layer and enables the effective utilization of energy for exposure and the blank to be used for this mask and process for production of such mask and blank.
Abstract: PURPOSE: To provide the phase shift mask which has high reliability as the phase shift mask for an exposure device using i rays and KrF excimer laser as light sources at the time of using the phase shift mask using a silicon oxide film as a phase shift layer and enables the effective utilization of energy for exposure and the blank to be used for this mask and process for production of such mask and blank. CONSTITUTION: A phase shift film has at least a transparent substrate 1 and the phase shift layer 3 consisting of oxide of silicon. The phase shift layer 3 of this phase shift mask is subjected to a heat treatment under a reduced pressure, more preferably under the reduced pressure and in an inert gaseous atmosphere after formation of the phase shift layer 3. COPYRIGHT: (C)1994,JPO&Japio

Patent
31 Mar 1993
TL;DR: The phase shift mask is provided with at least a light shielding section 7, light transmissive section, a light semi-transmissive section 3 and a phase shift section 5 especially in a transparent substrate and a major region section 13 is formed by a lighttransmissive sections, the sections 3 and 5 and at least some portion excluding the section 13 are formed by the section 7.
Abstract: PURPOSE:To provide a phase shift mask which has a half tone type phase shift section, is used in a projection exposing device that accepts a conventional photo-mask and forms a high precision patterns, to provide a manufacturing method that easily produces the above phase shift mask and to provide a blank to be used for the manufacturing method CONSTITUTION:The phase shift mask is provided with at least a light shielding section 7, a light transmissive section, a light semi-transmissive section 3 and a phase shift section 5 especially in a transparent substrate and a major region section 13 is formed by a light transmissive section, the sections 3 and 5 and at least a portion excluding the section 13 is formed by a section 7

Patent
23 Jul 1993
TL;DR: In this article, a phase shift mask is constituted of the translucent phase shift film which generates the absorption to the exposure light on a transparent quartz substrate, such as KrF excimer laser SOG(spin on glass), silicon phosphorus glass, silicon phosphorus boron glass, org high-polymer film, etc.
Abstract: PURPOSE:To improve the resolution on a photographing surface by constituting a phase shift film of a translucent material which generates absorption to exposure light CONSTITUTION:This phase shift mask is constituted of the translucent phase shift film which generates the absorption to the exposure light on a transparent quartz substrate 11 which is transparent to the exposure light, such as KrF excimer laser SOG(spin on glass), silicon phosphorus glass, silicon phosphorus boron glass, org high-polymer film, etc, are used as the essential material of the phase shift film 12 These films can be constituted by a vapor growth method The transmittance of the phase shift film to the exposure light is set at 40 to 90%, by which the resolution rate is additionally improved Fine working down to a min line width of 02mum is possible if such mask for optical exposure is used

Patent
Hiroshi Miyatake1
06 Apr 1993
TL;DR: In this paper, a method to mend a black defect and a white defect of a phase shift mask pattern so that the mended mask pattern has an accurately defined pattern has been proposed.
Abstract: A method to mend a black defect and a white defect of a phase shift mask pattern so that the mended phase shift mask pattern has an accurately defined pattern. In the vicinity of a black defect and the area around the same, a mending phase shifter is formed into a thickness twice as large as the thickness d of a phase shifter. All light beams through a black defect area are nearly 0 degree out of phase with a non-phase-shifted light beam, thereby the phase shift mask pattern having the black defect becoming a phase shift mask pattern with an accurately defined pattern. In a similar manner, every light beam through a white defect area is nearly 180 degree out of phase with a non-phase-shifted light beam. As a result, a mended phase shift mask pattern has an accurately defined pattern.

Patent
11 Jun 1993
TL;DR: In this paper, the phase shift mask has a light shield film, a phase shifter, and matching marks 12 and 12' on a substrate, and the matching marks are of size smaller than a resolution limit or provided on the film.
Abstract: PURPOSE:To form the fine pattern of the mask or phase shift mask with high precision. CONSTITUTION:The phase shift mask has a light shield film, a phase shifter, and matching marks 12 and 12' on a substrate, and the matching marks 12 and 12' are of size smaller than a resolution limit or provided on the light shield film. When the pattern of the phase shifter of the phase shift mask is positioned with the matching marks 12 and 12', drawn, and formed, the matching marks are provided where the formation of an element pattern is not impeded or deleted after the pattern forming. While the pattern is positioned repeatedly with the matching marks at desired intervals of time, the pattern is drawn by irradiation with an electron beam to form the pattern of the light shield film and phase shifter.

Patent
23 Feb 1993
TL;DR: In this article, the phase shift mask with a light transmission part of the main region part and a phase shift part was used to enable transfer exposing with a high resolution effect to be performed.
Abstract: PURPOSE:To enable transfer exposing with a high resolution effect to be performed and a phase shift mask to be used for the conventional steppers as it is by forming the phase shift mask with a light transmission part of the main region part and a phase shift part and forming at least a part of the periphery part exclusive of the main region part with a light shielding part. CONSTITUTION:A transparent substrate 1 is an optically transparent material as a material for photomasks and an etching stopper layer 2 is a material having high transparency to an exposing wavelength, although the adequate material is selected according to an etching method. Further, a phase shift layer 3 is preferably an optically transparent material and its film thickness is preferably set at the film thickness at which the phase inversion quantity of transmitted light correspond to 180 deg.. A light shielding layer 5 consists of a metal and metal oxide. Finally, a photoresist layer 7 is provided and is subjected to exposing and developing. Only the light shielding film 5 of the main region part 11 is removed by etching. Further, a translucent light shielding film 15 is formed. Patterns are then formed by executing resin coating, electron beam plotting and developing. The translucent light shielding layer 15, the light shielding layer 5 and further the phase shift layer 3 are etched away with these patterns as a mask.

Patent
20 Aug 1993
TL;DR: The phase shifter is constituted of a gelatin layer 1 which is provided in the unexposed part region on a transparent substrate 3 and does not contain a silver component and a silver salt-contg. gelatin layer provided by having a level difference from the gelatin layer.
Abstract: PURPOSE:To simplify the stage for forming a phase shifter and to improve a phase shift effect. CONSTITUTION:The phase shifter is constituted of a gelatin layer 1 which is provided in the unexposed part region on a transparent substrate 3 and does not contain a silver component and a silver salt-contg. gelatin layer provided by having a level difference from the gelatin layer 1 in the exposed part region adjacent to the unexposed part region. The intricate stage for forming the phase shift mask is simplified and the surface contamination of the phase shifter is prevented. The dealing with light of short wavelengths of (i) line or below is possible for the excellent transmissivity of the gelatin and the free adjustment of phase differences is possible. There is an effect of expanding the width of the phase shift effect. Further, the silver salt-contg. gelatin layer existing in the exposed part regions of the pattern parts is reduced. There is thus advantage that even the concn. of the blacked silver salt 2 is freely controllable.

Patent
08 Jul 1993
TL;DR: The phase shift mask has a phase shifting Sn layer formed on a transparent glass substrate (20). The layer is formed by chemical vapour deposition to a thickness equal to a number (one less than the refractive index) of half-wavelengths.
Abstract: The phase shift mask has a phase shifting Sn layer formed on a transparent glass substrate (20). The layer is formed by chemical vapour deposition to a thickness equal to a number (one less than the refractive index) of half-wavelengths. Patterned photoresists are applied before and after 02 ion implantation, leaving regularly spaced light-screening regions (21b) sepd. by ZnO (24) of the same thickness. No additional conductive layer is needed, so that charging under electron beam irradiation is prevented. ADVANTAGE - The mask has a smooth surface with light-screening and phase-shifting layers in the same plane. Mfr. is simplified and cost reduced with an inexpensive metal-oxide phase-shift layer.

Patent
07 Dec 1993
TL;DR: In this paper, a phase shifter is modified with a focused ion beam of 10 kev or less and an ion-filled layer, different from a shifter structural element, is formed on the surface of a molten silica substrate.
Abstract: PURPOSE:To provide a method of recovering a mask which has a lower transmissivity or not and to realize high-precision modification which allows easy detection of an etching terminal by modifying the recessed-shape defects of a phase shifter through the buildup of local points. CONSTITUTION:Protruded-shape defects 4 are removed by FIB assist etching and recessed-shape defects 4 are dipped around at a desired depth. If a phase shifter is made of silicon or its compound, gas including fluorine, chloride or bromine is used. If it has an organic film, O2, O3 or NO2 gas is used. After the defects are removed by spatter etching, damaged layers are removed by ion assist etching using XeF2 gas. A silicon oxide film or a silicon nitride film is built up in the recessed defects 4 by using focused ion beam of 10kev or less and modified. In so doing, An ion-filled layer, different from a shifter structural element, is formed on the surface of a molten silica substrate 1 and a phase shifter is additionally formed on the upper layer.

Patent
30 Nov 1993
TL;DR: In this article, the phase shift mask of a halftone type which is produced relatively simply in a short period of time by providing the outer peripheral parts of normal patterns with light shielding bands of a prescribed width is presented.
Abstract: PURPOSE: To provide the phase shift mask of a halftone type which is produced relatively simply in a short period of time by providing the outer peripheral parts of normal patterns with light shielding bands of a prescribed width. CONSTITUTION: The phase shift photomasks 1, 11, 21 of a halftone type are formed by providing the outer peripheral parts of the normal pattern regions 2, 12, 22 with the light shieldable bands 3, 13, 23. Namely, these photomasks are so composed that exposing of the parts exclusive of the prescribed regions is prevented by these bands coupled with a mechanical shutter and that the photosensitive resist on a wafer is not sensitized in the boundary parts by each of respective step exposing at the time of step and repeat exposing. These light shieldable bands 3, 13, 122 are formed of carbon films or metallic films mainly composed of chromium or molybdenum, etc., in the outer peripheral parts of the normal patterns, by which the application of methods for forming metallic films by a carbon film depositing method by irradiation with ion beams, low-temp. sputtering method or laser CVD method is made possible for production of the light shielding bands 3, 13, 23. The easy and rapid production of the light shielddable bands 3, 13, 23 is made possible. COPYRIGHT: (C)1995,JPO