Method for making element
AssigneeCanon Kabushiki Kaisha
InventorsYasuyuki Unno, Ichiro Tanaka
Life of this patent
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Abstract
A SiO2 thin film is formed on a SiO2 substrate provided with a binary-type diffractive element by a radiofrequency sputtering process so as to cover the fine irregularities formed on the substrate caused by misalignment of masks in the production process. This film planarizes the surface having the fine irregularities and thus prevents a decrease in diffraction efficiency.
Claims17
A method of making an optical element comprising the steps of:
- forming on a substrate a multilevel pattern having one or more errors on faces of different levels;
- and
- forming on the faces of the different levels a substantially flat light-transmissive film to planarize the faces of the different levels so as to cover the one or more errors,
- wherein the one or more errors include at least one of depressions and protrusions formed on the faces of the different levels.
A method of making an optical element comprising the steps of:
- forming on a substrate a multilevel pattern by a lithographic process having one or more errors on the faces of the different levels;
- and
- forming a film having a refractive index which is the same as that of the multilevel pattern on the faces of all levels of the multilevel pattern to planarize the faces of all of the levels so as to cover the errors,
- wherein the errors include at least one of depressions and protrusions formed on the faces of the different levels.
A method for making an optical element comprising the steps of:
- repeating a plurality of times of series of steps including a step of applying a resist to a substrate, a pattern transfer step, an etching step and a resist removal step to form a multilevel element pattern on the substrate which includes one or more errors on the faces of the different levels;
- and
- forming a film having a refractive index which is the same as that of the multilevel element pattern on the faces of all levels of the multilevel pattern to planarize the faces of all of the levels so as to cover the errors,
- wherein the errors include at least one of depressions and protrusions formed on the faces of the different levels.
A binary-type diffractive optical element comprising:
- a multilevel pattern, formed on a substrate, having one or more errors on faces of different levels;
- and
- a substantially flat light-transmissive film, formed on the faces of the different levels, to planarize the faces of the different levels so as to cover the one or more errors;
- wherein the one or more errors include at least one of depressions and protrusions formed on the faces of the different levels.
A binary-type diffractive optical element comprising:
- a multilevel pattern formed on a substrate by a lithographic process, the multilevel pattern having one or more errors on faces of different levels;
- and
- a film, having a refractive index the same as that of the multilevel pattern formed on the faces of all levels of the multilevel pattern, to planarize the faces of all levels so as to cover the errors;
- wherein the errors include at least one of depressions and protrusions formed on the faces of the different levels.
A binary-type diffractive optical element comprising:
- a multilevel element pattern formed on a substrate by repeating a plurality of times a series of steps including the step of applying a resist to a substrate, a pattern transfer step, an etching step, and a resist removal step, the multilevel element pattern including one or more errors on faces of the different levels;
- and
- a film, having a refractive index that is the same as that of the multilevel element pattern formed on the faces of all levels of the multilevel pattern, to planarize the faces of all levels so as to cover the errors,
- wherein the errors include at least one of depressions and protrusions formed on the faces of the different levels.
Dependencies are inferred from the claim text.