Photocopying – Projection printing and copying cameras – Focus or magnification control
Reexamination Certificate
1999-06-28
2001-10-16
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Focus or magnification control
C355S053000, C356S450000, C356S485000, C356S488000
Reexamination Certificate
active
06304318
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lithography system and a method of manufacturing devices using the lithography system. The lithography system and method of manufacturing devices using the lithography system are successfully adaptable to a method and system for manufacturing microscopic lines and spaces, or more particularly, to a method and system for manufacturing semiconductor devices using a diffraction grating. The semiconductor devices include optical devices, a semiconductor laser, and devices to be integrated into a semiconductor integrated circuit.
2. Description of the Related Art
According to a first method of forming a pattern of lines and spaces that has been adopted in the past, two-beam interference fringes are, as shown in
FIG. 1
, produced on a substrate to which a photosensitive agent is applied. The substrate is developed after being exposed. A pattern of lines and spaces is formed using the photosensitive agent. The substrate is then etched, while being masked with the pattern of lines and spaces formed with the photosensitive agent. The pattern of lines and spaces is thus drawn on the substrate.
Referring to
FIG. 1
, light emanating from a coherent light source such as a laser is bifurcated by a beam splitter
101
, reflected by mirrors
102
and
103
, and crossed on a substrate
104
. At this time, interference fringes, or in other words, a pattern of lines and spaces is formed in a two-beam crossing area
105
. Assuming that an angle of incidence of the light beams is &thgr; and a wavelength provided by the coherent light source is &lgr;, the pitch P between adjoining lines and spaces of the pattern is expressed as follows:
P=&lgr;/(2 sin &thgr;)
For example, when a He—Cd laser providing a wavelength of &lgr;=325 nm is used as the coherent light source, and the angle of incidence &thgr; is 60°, a pattern of lines and spaces having a pitch P=0.188 um (0.1 um or less between adjoining lines) can be drawn.
The foregoing two-beam interference fringes-based lithography method has the features described below. One of the features lies in that the cost of manufacturing is lower than that required by step-and-repeat photolithography method with demagnification. According to the step-and-repeat photolithography method with demagnification, a pattern is drawn on a mask using an electron-beam plotter and then projected on a substrate using a step-and-repeat photolithography system with demagnification. Another feature lies in that it is easier to draw a pattern with a pitch between adjoining lines and spaces set at 0.15 um or less than it is according to the step-and-repeat photolithography method with demagnification. The step-and-repeat photolithography method with demagnification adopts an excimer laser, which is currently a mainstream laser, as a light source. Another feature is a higher resolution than that offered by the step-and-repeat photolithography method with demagnification.
However, for example, a semiconductor device can be produced by overlaying numerous layers of patterns of circuits on a substrate (wafer). For exposing the wafer in order to form patterns of circuits of the second and subsequent layers, each pattern of the circuits to be formed must be highly precisely aligned with each shot location on the wafer. At each shot location, a pattern of circuits has already been formed. No practical method of directly controlling a location to be exposed to interference fringes has been implemented in existing interference fringes-based lithography systems. The interference fringes-based lithography systems must be further innovated so that they can be used to manufacture devices to be integrated into a semiconductor integrated circuit. For manufacturing the devices, patterns of circuits must be overlaid successively.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a lithography system capable of accurately exposing a desired location on a substrate (wafer) to desired interference fringes, and a method of manufacturing devices using the lithography system.
In a first aspect, the present invention provides a lithography system for exposing a photosensitive member. The system includes a photosensitive member placement unit and an interference optical system producing interference fringes on the photosensitive member so that the interference fringes will be transferred to the photosensitive member. The interference fringes are aligned based on detected light having passed through the interference optical system.
In another aspect, the present invention provides a lithography system for exposing a substrate to interference fringes. The system includes interference fringes producing means, interference fringes control means for controlling the interference fringes produced by the interference fringes producing means, position-of-interference fringes detecting means for detecting positional information of the interference fringes, position-of-substrate detecting means for detecting positional information of the substrate, and a substrate stage. The interference fringes are positioned by the interference fringes control means, based on the positional information of the interference fringes, which is detected by the position-of-interference fringes detecting means, the substrate is positioned based on the positional information of the substrate detected by the position-of-substrate detecting means, and the interference fringes are thus positioned in a predetermined place on the substrate.
In yet another aspect, the present invention provides a lithography system for projecting a pattern drawn on a reticle onto a substrate. The system includes interference fringes producing means, interference fringes control means for controlling interference fringes produced by the interference fringes producing means, position-of-interference fringes detecting means for detecting positional information of the interference fringes, position-of-substrate detecting means for detecting positional information of the substrate, reticle holding means for holding a reticle, reticle alignment means, a step-and-repeat photolithography unit with demagnification, illuminating means for illuminating the reticle held by the reticle holding means so that a pattern drawn on the reticle will be demagnified and projected onto the substrate by the step-and-repeat photolithography unit with demagnification, and a substrate stage for holding the substrate. The interference fringes are positioned by the interference fringes control means, based on positional information of the interference fringes, which is detected by the position-of-interference fringes detecting means, the reticle alignment means aligns the reticle with the step-and-repeat photolithography unit with demagnification, the substrate is positioned relative to the interference fringes according to positional information of the substrate detected by the position-of-substrate detecting means, and exposed to the interference fringes, the substrate is positioned in the step-and-repeat photolithography unit with demagnification according to positional information of the substrate detected by the position-of-substrate detecting means, and then a pattern drawn on the reticle is projected onto the substrate.
In still another aspect, the present invention provides a method of manufacturing devices includes the steps of aligning interference fringes according to detected light that has passed through an interference fringes production interference optical system, producing interference fringes on a photosensitive member using the interference optical system so that the interference fringes will be transferred to the photosensitive member, and forming circuits according to a pattern drawn on the photosensitive member by transferring the interference fringes.
In still another aspect, the present invention provides a method of manufacturing devices including the steps of exposing a substrate using a lithography system, the lithography syst
Adams Russell
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Fuller Rodney
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