Showing papers on "Resist published in 1977"

Line‐Profile resist development simulation techniques

Abstract: The relative advantages and disadvantages of three different algorithms are compared for simulating the time evolution of two-dimensional line-edge profiles produced by a locally rate dependent surface etching phenomenon. Simulated profiles typical of optical projection printing and electron-beam and X-ray lithography of micron-sized lines in resist and etching of ion-implanted SiO2 are used as a basis of comparison. One of the algorithms is a cell-by-cell removal model used earlier by Neureuther and Dill. One of the newly developed algorithms employs ray tracing; it can be shown that the path followed by a point on a front between the developed and undeveloped regions can be calculated using ray-optic equations. The other new algorithm uses a string of points initially on the surface of the exposed resist. The points on the string advance perpendicular to the local direction of the string; with time the string of points moves down into the resist, replicating the action of a developer. We compare the computing cost, convenience, and accuracy of the algorithms.

A new inorganic electron resist of high contrast

Abstract: A novel inorganic electron resist is proposed. It is shown that the electron irradiation on a stacked layer composed of a thin Ag film over a layer of Se‐Ge chalcogenide amorphous glass enhances diffusion of Ag into Se‐Ge glass, in the same manner as in the case of photodoping. The Ag‐doped Se‐Ge film becomes almost insoluble in alkaline solutions. A negative‐type electron resist is realized by applying this effect. This inorganic electron resist is proved to exhibit an extremely high contrast (γ∼8). The sensitivity is 4×10−5 C/cm2 at 5 kV. It is confirmed that fine‐pattern delineation of less than 0.3 μm linewidth is possible.

Method of manufacturing high density fine line printed circuitry

Abstract: The method of manufacturing printed circuitry with sufficiently high resolution to permit line densities of at least 1 mil lines on 3 mil centers includes the steps of placing a thickness of dry film photoresist on a smooth, polished substrate or carrier optionally, applying a thin lubricating layer of spray wax to the exposed surface of the photoresist, wringing a mask defining a desired conductive circuit pattern into high integrity, intimate contact with the surface of the resist, exposing and developing the resist to remove the resist from the smooth surface in regions where the conductive circuit pattern is to be formed, electroplating the conductors within the voids formed in the resist; removing all remaining resist, laminating a flowable dielectric material to the smooth surface of the substrate and the conductive circuit pattern, and removing the laminate material and conductive circuit pattern from the smooth surface. If desired, conductive via interconnects can be selectively formed and additional layers of circuit patterns can be formed atop the first high resolution layer.

X-ray lithography

Abstract: The advent of X-ray lithography as a natural compliment to electron beam pattern generation and photolithography seems to be filling a need in the fabrication of submicron devices. The X-ray technique, which is simple for single level devices, lags behind other lithographies in registration techniques. However, its proven high resolution capabilities is responsible for the increased interest in further development. At present a, variety of mask substrates are being evaluated with no one material exhibiting an overwhelming advantage. The type of substrate used is closely coupled to the permissable wavelength of the X-ray source. The X-rays used for lithography to date vary from Rh L (4A) up to CK (44A). Each wavelength shows a distinct advantage and disadvantage. For example, at short wavelengths substrates can be relatively massive but resists are less sensitive and high resolution masks have low contrasts. At longer wavelengths, resists are more sensitive and masks have higher contrast, but defects due to dust are more probable. The use of more than one X-ray source could fulfill the requirements imposed by mask making and device fabrication. High throughput for both masks and device require both foster resists and higher intensity X-ray sources.

Electro-lithography method

Abstract: An electro-lithography method suitable for forming a high resolution pattern in an electron sensitive resist material is disclosed. This technology permits the inexpensive high resolution reproduction of masks for use in integrated circuits and magnetic bubbles. The method involves the application of a pulsed, electric field to two parallel electrodes having an electron beam resist layer positioned on one of the electrodes and a mask positioned between the second electrode and the resist layer. The mask forms a gap having a thickness of 10 -4 m to 10 -5 m with the resist layer.

Novel resist spinning head

Abstract: A resist spinning head for preventing photoresist, or electron and X-ray resist from flowing to the edge of the wafer when spin coating in a photoresist spinner, which includes the use of a tapered top plate having a knife-edge contact to the surface of the wafer so as to seal the top of the wafer at an outer ring and prevent resist from flowing under the top plate; whereby the resist is guided, during spinning, by the tapered top surface to the edge of the plate and off the head. The tapered top plate is pressed against the wafer and secured by a spring biasing means to a spinner motor shaft.

Method of using a o-quinone diazide sensitized phenol-formaldehyde resist as a deep ultraviolet light exposure mask

Abstract: A photolithographic method wherein a mask is made by pattern exposing and developing a o-quinone diazide sensitized phenol-formaldehyde resist layer, the formed resist mask then being used directly as an exposure mask for a layer of deep ultraviolet (less than 3000A) sensitive resist such as an alkyl methacrylate resist. Since alkyl methacrylate resists are not sensitive to light above 3000A and phenol-formaldehyde resists are opaque to light below 3000A, phenol-formaldehyde resists may be used directly as photoexposure masks for alkyl methacrylate resists using any broad band exposure light source which includes deep ultraviolet. The direct use of a phenol-formaldehyde resist layer as an exposure mask for an alkyl methacrylate resist layer allows more flexible and practical use of resist exposure techniques, including fabrication of an etch resistant mask of high aspect ratio and high resolution without fabrication of an intermediate metallic mask from a material such as chromium.

Dry processing of high resolution and high aspect ratio structures in GaAs-Al(x)Ga(1-x) As for integrated optics.

Abstract: The properties of ion-beam milling, rf-sputter etching, and plasma etching for the fabrication of high resolution integrated optical structures in GaAs and AlxGa1−xAs were investigated. The ion-beam milling rates for a 500-eV Ar beam were measured as a function of the angle of incidence for A2-1350 photoresist, GaAs, Al, Ti, and Ta in vacuum. For Ti and Ta, the ion-beam milling rates were measured for various O2 partial pressures in the target chamber. For the fabrication of high-resolution patterns, a technique was developed in which a very thin resist pattern is transferred by plasma etching into a layer of Ta prior to ion-beam milling. Both ion-beam milling and rf-sputter etching through the Ta metal mask were used for the fabrication of gratings in GaAs. From measurements made in this study, it was found that rf-sputter etching in an Ar atmosphere results in a resolution comparable to ion-beam milling at normal incidence, but the material removal efficiency is somewhat lower. Third-order Bragg diffraction gratings (period = 0.36–0.37 μm) for GaAs-AlxGa1−xAs heterostructure lasers and ridged stripes 10 μm wide and 1.5–2.0 μm deep have been prepared by these techniques. High-aspect ratio or skewed-profile gratings were obtained by selection of the ion-beam milling or rf-sputter etching conditions. As previously reported, these structures have been overgrown by MBE AlxGa1−xAs layers to form distributed feedback lasers.

Method for fabricating self-aligned semiconductor devices utilizing selectively etchable masking layers

Abstract: A method for fabricating self-aligned regions of semiconductor devices such as bipolar or field effect transistors using three masking layers which are selectively etchable with respect to each other on the surface of the semiconductor body. A dimensional mask is deposited over the three layers so that the set of all of the self-aligned impurity regions to be formed through the surface of the body are defined by etching the upper masking layer, with the intermediate layer acting as an etch-stop. Using conventional wet or dry resist processes, each subset of similar impurity regions may then be formed selectively through the intermediate and lower layers without the need for precisely aligning any subsequent mask.

Sensitive chlorine-containing resists for X-ray lithography

Abstract: New resists containing chlorine to enhance absorption to PdLα X-radiation at 4.37 A have higher sensitivity than currently available high-speed electron resists when used in a high-throughput PdLα X-ray exposure system developed by Maydan and coworkers. Of the three classes of materials examined the poly(chloroalkyl acrylates) have the best properties. The sensitivity and contrast of these negative resists are dependent on the amount of Cl present, the structure of the chloroalkyl side chain, the inclusion of reactive functional groups, and molecular weight. Contrast is found to decrease with increasing sensitivity achieved by either increasing molecular weight or incorporating more reactive glycidyl groups. We suggest that such behavior, which is not predicted by theories of radiationinduced crosslinking, has its origin in competitive formation of intramolecular crosslinks with the desired, intermolecular crosslinks. Poly(2, 3-dichloro-1-propyl acrylate) has been investigated in greatest detail. Samples of this polymer requiring a dose of 7 mJ/cm2 for 50 percent of the initial resist thickness (2 min exposure) have been used successfully to wet etch 1 μm features into SiO2, Al and Cr and 2 μm features into phosphosilicate glass. It has moderate resistance to ion milling and good resistance to plasma etching with Freon-based plasmas.

Method of forming thin film patterns by differential pre-baking of resist

Abstract: A method of depositing patterned thin films on an integrated circuit substrate which comprises first forming a layer of positive photoresist material on the substrate and then heating to partially cure the photoresist while maintaining the surface of the photoresist interfacing with the substrate at a lower temperature than the opposite surface of the photoresist which is being exposed to the heat. As a result of this expedient, the upper or exposed portion of the photoresist layer is cured to a greater extent than the lower portion at the interface with the substrate. Then, the photoresist layer is exposed to a selected pattern of light, after which developer for the photoresist material is applied. The developer will remove the less cured interfacing portion of the photoresist layer at a higher rate than the more cured upper layer to thereby form an aperture pattern through the photoresist layer corresponding to the light pattern wherein the apertures are respectively narrower at the opposite or exposed surface than at said interfacing surface. This produces the negative slope or "overhang" type lift-off mask which is considered to be critical to forming thin film patterns by lift-off techniques. Then, the selected thin film is deposited onto said substrate through the apertures utilizing the photoresist mask as a deposition mask, after which the remainder of the photoresist layer is removed, leaving the thin film pattern on the substrate.

Resist image hardening process

Abstract: Resist images are hardened so that they are flow resistant at elevated temperatures by coating the image with a layer of a quinone-diazide hardening agent and heating the image to cause the agent to react with the resist and form a hardened image.

Process for forming a high aspect ratio structure by successive exposures with electron beam and actinic radiation

Abstract: A high aspect ratio structure (with a large height-to-linewidth ratio) is formed on a substrate by means of two resist layers with different kinds of radiation to which they are sensitive, respectively, with an actinic radiation sensitive resist below and an electron sensitive resist above. In addition, a metallic film is shaped by means of exposure of the upper layer of resist to form a metallic mask through which the lower layer of resist is exposed. Exposure may be performed by a "subtractive" technique or an "additive" technique. In the case of the subtractive technique, the substrate is coated by a first actinic resist above which are deposited first a metallic film and then a top layer of electron resist. The top resist layer is exposed and developed and the metal layer is etched so the lower resist can be exposed and developed with the pattern formed in the metal, with the pattern shape originally exposed in the top layer of resist extending down to the substrate. In the additive technique, the pair of resists is deposited first with the actinic resist layer below and the electron resist layer above. The electron beam exposes the electron resist which is developed to provide openings. Then, a metallic layer is deposited and the electron resist which remains is removed with some of the metal in a lift-off step. The openings provided in the metal during the lift-off step are used as apertures for exposure of the lower resist layer to actinic radiation. The lower resist is developed, yielding a high aspect ratio structure as was done in the first case.

Method of making a negative exposure mask

Abstract: A negative exposure mask is prepared by forming a positive mask image of a first metal layer on a transparent substrate and applying a layer of resist which is exposed through the back of the substrate and developed to form a lift-off mask. The lift-off mask is used to form a negative mask image of a second layer of metal on the substrate in the areas not covered by the first metal layer. The first metal layer is then etched away to leave the negative mask image on the substrate.

Fine-line circuit fabrication and photoresist application therefor

Abstract: A method is disclosed for the production of thick and smooth layers of photoresist on the order of 2-15 microns thick. The substrate is flooded with resist as in the standard spin resist method, but instead of following the flooding step with spinning as usual, the second step is to provide a drying time for the flooded resist. Then at the end of the measured drying time, the resist is spun as usual. This can be used to produce fine line closely spaced circuitry in which the thickness of the lines in proportion to their width, or their aspect ratio, is large. Aspect ratios greater than 0.4 and as high as 1.5 are contemplated by the invention.

Method for removing resist layer from substrate with combustible gas burnoff

Abstract: Method and apparatus for removing a resist layer from a substrate surface of different material, such as a semiconductor slice, in the fabrication of an electronic structure, involving exposure of the resist layer to a flame from a combustible gas. The resist layer is employed as a mask in patterning the substrate surface via selective etching, diffusion, or other procedures and is removed from the substrate when it has served its purpose. The resist material may include not only light-sensitive resists more commonly termed "photoresists", but also electron beam-sensitive resists, and resists applied by stencil techniques. The resist layer is exposed to the flame for a period of time sufficient to decompose the resist material, the length of the exposure being a function of several factors, including the type of resist, the thickness of the layer, and the manufacturing processes to which the slice was subjected prior to the resist removal step. No vacuum or other special ambient atmospheric condition is required for this resist removal process, but the slice may be positioned on a belt or other mobile platform and the means for producing the flame may also be adjustable in order to effectively vary the parameters of exposure time and temperature, depending on the aforementioned factors.

Method of fabricating a printed circuit board with etched through holes

Abstract: A method of fabricating a printed circuit board is disclosed. The method comprises forming a patterned etch resist layer on a metal substrate and selectively etching the substrate to form a through hole with non-linear undercut walls. The etched metal substrate having the resist layer thereon is then coated with a dielectric powder to form a dielectric coat on the substrate having a sufficient through hole edge coverage.

Process using radiation curable epoxy containing resist and resultant product

Abstract: Negative resist compositions are based on carbonaceous polymers with substituent branches containing epoxy groupings. Exemplary materials which include, for example, a copolymer of glycidyl methacrylate and ethyl acrylate in which epoxy groupings are unesterified show high sensitivity, for example, to electron radiation and to X-rays. Resolution is sufficient to permit expedient fabrication of detailed resist patterns for integrated circuits. High adherence permits use of acid or base reagents and thermal stability permits use of ion milling for circuit fabrication.

Polymeric resist mask composition

Abstract: A polymeric resist mask composition thinly coated on a semiconductor substrate, wherein the prescribed portions of said resist mask are exposed to high energy rays such as electron beams, X-rays or ultraviolet rays for degradation, and the degraded portions of the resist mask are removed by an organic solvent to present a prescribed resist mask pattern on the semiconductor substrate, which comprises a halogenated polymethacrylic ester whose composition is expressed by the general formula ##STR1## (WHERE R denotes a halogenated alkyl radical including a halogen element selected from the group consisting of fluorine, chlorine and bromine, and at least one fluorine atom in case said radical contains chlorine or bromine and n indicates an average polymerization degree of 100 to 20,000) and an organic solvent for said halogenated polymethacrylate.

Variable pre-spin drying time control of photoresists thickness

Abstract: Resist is applied to a surface with a syringe, or other suitable dropper, equipped with a millipore filter to remove contaminants. The surface is completely flooded with resist. Resist is allowed to remain on the surface of the evaporated metal for a period of time prior to spin coating. Allowing resist to remain on the surface prior to coating produces a uniform film. For a 2 micron thick uniform resist coating, a minimum of 15 seconds is allowed prior to spinning while in the case of a 4 micron thick resist coating a much longer period is allowed. For the application of a 2 micron film, the resist material after partial drying for approximately 15 seconds is spun at 2000 rpm for 30 seconds. In order to apply a 5 micron thick resist film, resist is spun at 2000 rpm for 30 seconds after partial drying for approximately 10 minutes.

Resist development control system

Abstract: Apparatus provides an incident light beam which illuminates the surface of a resist coated grooved disc, having an exposure pattern of signal elements formed within the groove, with a light spot that spans a plurality of convolutions of the groove. As the resist coating is developed, portions of the resist coating corresponding to the exposure pattern are removed and the emerging structure of the signal elements serves as a diffraction grating which diffracts the incident light beam. Photodetector apparatus positioned to intercept a selected portion of the diffracted beam provides an output corresponding to the light power in the selected portion. Means responsive to the output of the photodetector are provided for directly indicating the achievement of a desired emerging signal element geometry in the region illuminated by the light spot to thereby control the resist development process.

New photoresists of cyclized butadlene polymers

Abstract: A new photoresist composed of cyclized cis-1, 4-polybutadiene has been developed. The resist has much higher sensitivity on exposure to ultraviolet light than the conventional resist from cyclized polyisoprene. This new resist has no resist-flow even at 250°C, and provides high resolution on baking at 200°C. Thermogravimetric analysis showed that the cyclized polybutadiene decomposes at temperature higher than cyclized polyisoprene.

Surface elastic wave element

Abstract: PURPOSE:To reduce the insertion loss of the surface elastic wave element, by burying the comb-line electrode within the hollow part of the piezoelectric substrate. CONSTITUTION:The resist 3 is applied to the quartz plate 1 to form a recess part on the plate 1. Then the aluminum 21 is buried through vapor deposition so as to just fill the recess part. After this, the resist 3 is deleted to remove the aluminum 20 on the resist 3, and then the aluminum is buried into the recess part of the plate 1. Thus a surface elastic wave element is obtained with a comb-line electrode formed. The electric line of force affects effectively and directly the electric field for said wave element, thus enhancing the converting efficiency of energy.

Pattern forming method

Abstract: PURPOSE: To make accurate the pattern size of the etched material formed by using the hardened film, by increasing the plasma-proof performance through hardening the remained resist film with ion injection of Ar, after performing exposure development for the resist film coated on the etched material. COPYRIGHT: (C)1979,JPO&Japio

Negative plate for photo mask

Abstract: PURPOSE: To obtain a photo mask patterned with high precision, by stacking a transparent conductive film, pattern formation film, and conductive film on a transparent substrate. CONSTITUTION: Transparent glass plate 1 is preheated and onto it, a mixed solution of SnCl 3 and SbCl 3 is sprayed, thereby forming transparent conductive film 4a. Next, Cr 2 O 3 2 and Sn04b are laminated. If this photo-mask negative plate is made electrically conductive through a terminal attached to coating 4b, the charge accumulation is prevented at the time of exposing the resist film formed on the plate to charge particles. Therefore, the ecposure amount to the resist film will not be decreased and unstable, and the pattern formed on the resist film has no exposure unevenness, so that a fine pattern will be formed on the photo mask with high precision COPYRIGHT: (C)1979,JPO&Japio

Invited: X-Ray Lithography

Abstract: X-ray lithography has been used in the fabrication of surface-acoustic-wave, bubble-domain, and silicon MOS devices and is well suited for replicating sub-micrometer linewidth patterns. In order to be applied in the commercial exposure of silicon IC devices, however, high power sources, sensitive resists, distortion free masks, multiple mask alignment, and repeatability of local mask-to-wafer gap will be required. These items are discussed from the point-of-view of developing design criteria for an X-ray lithography system optimized for 1/2 µm linewidths, 1/10 µm superposition, and exposure times under 200. For linewidths below 1/2 µm, copper (λ=13.3 A) or carbon (λ=44.7 A) sources are preferred. Recent progress in using the copper radiation to replicate grating patterns with linewidths of the order of 1000 A with sharp vertical sidewall profiles are described.

Removing method of high molecular compound

Abstract: PURPOSE: To facilitate resist removal in lithography process by performing plasma etching through the use of a mixed gas which is mainly composed of a gas containing oxygen atoms and is then added with a gas containing fluorine atoms. COPYRIGHT: (C)1978,JPO&Japio

Micropattern forming method

Abstract: PURPOSE: To secure the ideal adhesion between the resist and the mask in order to form a micropattern to the processed layer by giving the adhesive evaporation of the metal light sheilding layer directly on the photo resist and then obtaining the mask for photo resist patterning by patterning the evaporated light shielding layer. CONSTITUTION: Photo resist film 6 is coated on processed layer 5 on base 4, and metal light shielding layer 7 of Cr, Al, Au and the like is evaporated directly on film 6. Then highly sensitive electron resist film 8 is coated on the entire surface, and the exposure is given after the scribing exposure via the X-rays, the electron beams and others to form pattern 8'. After this, layer 7 is etched with pattern 8' used as the mask, and minute metal pattern 7' remains under pattern 8'. The exposure and development are given again to exposed film 6, and processed layer 5 is exposed with film 6' remaining. Then layer 5 is etched using the mask of the laminated layer film formed with patterns 8', 7' and 6', and the laminated film is removed to obtain desired pattern 5'. COPYRIGHT: (C)1979,JPO&Japio

Undulation pattern forming method

Abstract: PURPOSE:To enable mask patterns of inverted trapezoidal form of photo resist suitable for lift-off method to be formed on a signal recording medium such as video disc original plate by recording on positive type photo resist through laser exposure. CONSTITUTION:A metal layer 8 such as of Cr of surface reflectance 60% is evaporated on a glass substrate 1 of good flatness. Over this is coated positive type photo resist 2, which is then prebaked. Next, the laser light 9 from an Ar laser is radiated to the moving substrate 1, whereby signal recording is effected on the resist 2. The portions having been exposed by the light 9 are removed by developing, whereby photo resist patterns 10 of inverted trapezoidal form an formed. Next, a metal layer 6 such as of Al is evaporated on the layer 8 and the resist 2. Thereafter, the resist 2 is removed and the layer 6 by lift-off on the resist 2 is peeled, then the evaporated metal undulation patterns 7 are obtained on the layer 8.

Index and surface simultaneous modulation in negative photoresist films

Abstract: A considerable index-of-refraction modulation effect was found to occur in a negative photoresist when molecular-mass-diffusion is facilitated. This resist may then be used either as an autodeveloping index-modulation recording material, or as a surface-modulation recording material or both, depending on the procedure utilized for recording and developing. Surface and index modulation are studied in a thin resist film by recording a 100 l/mm grating on it and measuring its diffraction spectrum. An approximative though simple method for analyzing this spectrum used in finding out the corresponding grating transmission phase modulation is briefly exposed.