# US 5,350,605 A · Process for the preparation of an optical structure and optical structure obtained thereby > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,350,605 A - Document ID: US5350605A - Status: Granted - Kind: A - Application number: 08/148,422 - Filed: 1993-11-08 - Granted: 1994-09-27 - Earliest claimed: 1991-06-12 - Assignees: L'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude - Inventors: Jean-Christophe Rostaing; Francois Coeuret - Web page: https://patentgrep.com/patent/US5350605A ## CPC - G02B 1/105 - G02B 1/14: Protective coatings, e.g. hard coatings - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract The invention concerns the preparation of an optical structure. On a polymeric substrate there is first provided a surface activation, and the deposit of a layer of SiO.sub.2, 2000 .ANG. thick after which there is a deposit of a plurality of functional layers and finally a deposit of SiO.sub.2, 3 microns thick followed by a deposit of Si.sub.3 N.sub.4 /SiO.sub.x N.sub.y 3 microns thick, the latter being produced under radio-frequency polarization. The thus obtained optical structure has properties of adhesiveness, resistance to abrasion and to thermal impacts. ## Claims ### Claim 1 A process for producing an optical structure comprising a silicon-based coating on an optical polymeric substrate, comprising the following consecutive steps: (a) plasma-activating a surface of the substrate with plasma based upon a gaseous mixture containing argon to form an activated surface; (b) depositing a first layer of SiO.sub.2 onto the activated surface by a plasma enhanced chemical vapor deposition technique from silane and oxygen to form a first layer having a thickness of from about 2 to 5 microns; (c) coating said first layer by a plasma enhanced chemical vapor deposition technique while the substrate is subjected to radio-frequency biasing with a second layer formed of a silicon nitride. ### Claim 2 The process for producing an optical structure comprising a silicon-based coating on an optical polymeric substrate, comprising the following consecutive steps: (a) plasma-activating a surface of the substrate with a plasma based upon a gaseous mixture containing argon to form a plasma-activated surface; (b) depositing a first layer of SiO.sub.2 onto the activated surface by plasma enhanced chemical vapor deposition from silane and oxygen to form a first layer having a thickness of from 2 to 5 microns; (c) coating said first layer by plasma enhanced chemical vapor deposition with a second layer, said second layer comprising a complex having a composition intermediate between SiO.sub.2 and Si.sub.3 N.sub.4 with a minimum of Si--Si bonds while the substrate is subjected to radio-frequency biasing. ### Claim 3 (depends on 1) The process according to claim 1 wherein the nitride compound of silicon contains silicon, hydrogen and nitrogen. ### Claim 4 (depends on 1) The process according to claim 1 wherein said second layer has a thickness of from 2 to 50 microns. ### Claim 5 (depends on 1) The process according to claim 1 further comprising depositing onto the activated surface a silicon-based under-layer by plasma enhanced chemical vapor deposition from silane. ### Claim 6 (depends on 2) The process according to claim 2 further comprising depositing onto said activated surface a silicon-based under-layer by plasma enhanced vapor chemical vapor deposition from silane. ### Claim 7 (depends on 5) The process according to claim 5 wherein at least one optical layer is deposited between said under-layer and said first layer. ### Claim 8 (depends on 6) The process according to claim 6 wherein at least one optical layer is deposited between said under-layer and said first layer. ### Claim 9 (depends on 5) The process according to claim 5 wherein the intermediate layer has a thickness of from 100 to 200 Angstroms. ### Claim 10 (depends on 6) The process according to claim 6 wherein said intermediate layer has a thickness of from 100 to 200 Angstroms. ### Claim 11 (depends on 1) The process according to claim 1 wherein the plasma activation of the surface is effected with a plasma selected from the group consisting of Ar/O.sub.2 plasma and successive Ar and Ar+NH.sub.3 plasmas. ### Claim 12 (depends on 2) The process according to claim 2 wherein the plasma activation of the surface is effected with a plasma selected from the group consisting of Ar/O.sub.2 plasma and successive Ar and Ar+NH.sub.3 plasmas. ### Claim 13 (depends on 2) The process according to claim 2 wherein the radio-frequency biasing of the substrate is performed so as to adjust the compressive stress of the layer at room temperature. ### Claim 14 In a process for producing an optical structure comprising a silicon-based coating on an optical polymeric substrate comprising plasma-activating a surface of the substrate, depositing a first layer of SiO.sub.2 onto the activated structure by plasma enhanced chemical vapor deposition technique from silane and oxygen to form a first layer; the improvement comprising coating said first layer by a plasma enhanced chemical vapor deposition technique with a second layer formed from a silicon nitride compound while the substrate is subjected to radio-frequency biasing. ### Claim 15 In a process for producing an optical structure comprising a silicon-based coating on an optical polymeric substrate comprising plasma-activating a surface of the substrate, depositing a first layer of SiO.sub.2 onto the activated structure by plasma enhanced chemical vapor deposition technique from silane and oxygen to form a first layer; the improvement comprising coating said first layer by a plasma enhanced chemical vapor deposition technique with a second layer of a complex of a composition which is intermediate between SiO.sub.2 and Si.sub.3 N.sub.4 with a minimum number of Si--Si bonds while the substrate is subjected to radio-frequency biasing.