Materials for Use in a Durable Selectively Semitransparent Photomask

Thin films of a new iron oxide phase, β‐Fe2O3 , were prepared by chemical vapor deposition (CVD) from tris(trifluoroacetylacetonato) iron (III) at 300°C in the presence of oxygen onto a variety of substrates. The films were characterized by x‐ray diffraction analysis, scanning electron microscopy, and Mössbauer spectroscopy. For the latter measurements the films were prepared from enriched 57Fe2O3 . The ultraviolet, visible, and infrared spectra of the films were also recorded. The iron (III) oxide phase prepared was bcc having the bixbyite structure, Ia3 space group and the lattice constant a0=9.393Å . There are 16 formula molecules to the unit cell and the two iron atoms occupy two nonequivalent distorted octahedral lattice sites: 3̅ (8b); 2(24d).

mentioning

confidence: 99%

β Fe2 O 3: Preparation of Thin Films by Chemical Vapor Deposition from Organometallic Chelates and Their Characterization

Ben‐Dor

Fischbein

Felner

et al. 1977

“…The visible-ultraviolet absorption spectra for Fe203 suitable for use as a photomask is well established (2) and is shown in Fig. 2 (dashed curve).…”

Section: Methodsmentioning

confidence: 83%

Poly(Vinylferrocene)—Conversion to an Oxidized Iron System Suitable for Use as a Semitransparent Hard Photomask

Thompson¹

1975

A novel technique for the production of iron oxide films from a polymer precursor is described. Films of poly(vinylferrocene) (PVFc) can be converted to iron oxide films in either a 2O0W oxygen plasma at room temperature or thermally in oxygen at 380~ The thermal decomposition appears to be more suitable for routine use, and process parameters for this technique have been optimized. The thermal conversion has been studied using infrared, visible, and u.v. spectroscopy and a decomposition reaction proposed. The iron oxide films prepared from PVFc have chemical and physical properties similar to the iron oxide films prepared using the iron pentacarbonyl process. Films prepared from PVFc are presently being evaluated for use as semitransparent photolithographic masks.The use of iron oxide for the fabrication of hard, semitransparent masks for use in the manufacture of integrated circuits is gaining rapid acceptance (1). Although the film material is primarily FeeOs, the exact structure is far more complicated than a pure Fe2Q system. Iron oxide was chosen from a large group of transition metal oxides and mixed oxides as having the best combination of chemical and physical properties required for use as a transparent mask material (2). The relevant properties are given by Peters et al. (3) as: (i) <1% transmission in the 360-400 nm spectral region; (it) >30% transmission at the sodium D line "(589 nm); (iii) an etching rate compatible with conventional photolithographic processes and materials; (iv) in addition, the physical integrity of the film (hardness, abrasion resistance, etc.) must be sufficient to sustain the abuses of routine handling. Three techniques ,are presently available for the deposition of thin films of iron oxide. The first is a chemical vapor deposition scheme using Fe(CO)~ developed by MacChesney et al. (4). Iron pentacarbonyl is thermally decomposed at temperatures in the 130 ~ 200~ range in an oxidizing atmosphere (CO2 + O2) on glass substrates. Films prepared by this technique have excellent mask properties, and this is presently the technique of choice for mask film manufacture. The. only substantial disadvantage of the procedure is using a poisonous compound, Fe(CO)2. A second deposition technique involving sputtering has been devised by Sinclair et al. (2, 3) for depositing Fe205films. The sputtering techniques used were conventional with the exception that it was found necessary to introduce CO2 + O2 as a discharge gas in order to increase the solubility of the deposited Fe205 films to an acceptable level for etching. The exact role that CO2 plays is not clear, but it appears likely th,at the pre sence of iron carbonate in films leads to increased solubility (3). The sputtering technique produces films which meet all mask requirements with the only disadvantage being that the process is slow and requires expensive vacuum equipment. The third general procedure, one similar to the process described in this paper, involves the decomposition of an organometallic compound in an oxidizing atmosp...

“…In the light of the above requirements, we have examined a variety of transition metal oxides in addition to those screened by Sinclair et al (1). It is recognized that the quality of the circuits is largely dependent on the quality of the masks.…”

Section: Ibm Thomas J Watson Research Center Yorktown Heights New mentioning

confidence: 99%

“…The lack of transparency of current materials used for contact mask fabrication, such as chromium and photographic emulsions, makes it very difficult to visually align the mask with the structures underneath it, especially when the ratio of opaque to clear area is large. Recently, a number of new materials that are transparent in the visible region and opaque in the ultraviolet around 4000A have been suggested for STP applications (1,2,3). The favorable optical characteristics of these materials permit the accurate visual alignment of the mask and make it possible to use much finer structures for contact printing.…”

Section: Ibm Thomas J Watson Research Center Yorktown Heights New Yor...mentioning

confidence: 99%

“…The general material requirements for STP applications are: (a) zero transmission in the region below 3500A to facilitate masking; (b) transmission of greater than 30% at 5890A to permit visual alignment; (c) easy etchability in solvents compatible with photoresist processing; and (d) reasonable hardness to provide durability. In the light of the above requirements, we have examined a variety of transition metal oxides in addition to those screened by Sinclair et al (1). Among these, thin films of GaFeOs, prepared by sputtering techniques, and hexaferrite of the composition PbFe12019 (magnetoplumbite), prepared by the CVD method, appear to be promising for STP applications.…”

Section: Ibm Thomas J Watson Research Center Yorktown Heights New Yor...mentioning

confidence: 99%

See 1 more Smart Citation

Preparation and Properties of Hexaferrite Films

Taylor¹,

Sadagopan²

1972