Patent Description:
Technologies for uniformly irradiating a predetermined plane with laser light emitted from a light source such as a semiconductor laser have conventionally been proposed. For example, in a light irradiation apparatus in which a plurality of cylindrical lenses in a cylindrical lens array divide laser light incident from a light source part into a plurality of light fluxes and another lens superimposes irradiation regions of the light fluxes on one another on an irradiation plane, an optical path length difference generation part is provided between the light source part and the cylindrical lens array. The optical path length difference generation part includes a plurality of transparent parts that produce differences in optical path length among them that are longer than the coherence length (coherence distance) of the laser light, and light that has passed through the plurality of transparent parts respectively enters the plurality of cylindrical lenses. This prevents interference fringes from appearing and achieves uniformity of the intensity distribution of illumination light that is emitted onto the irradiation plane (see, for example, <CIT> as one example of such an apparatus).

The above-described light irradiation apparatus is provided with a light condensing part that, in the case of making a linear cross section of light on the irradiation plane, causes the plurality of light fluxes to converge on the same position of the irradiation plane when viewed in the direction of arrangement of the cylindrical lenses. However, in the case where parallelism of the entrance and exit surfaces of the transparent part varies among the transparent parts or parallelism of the entrance and exit surfaces of the cylindrical lens varies among the cylindrical lenses when viewed in the above direction of arrangement, the light condensing positions of the plurality of light fluxes on the irradiation plane will be shifted from one another in a direction perpendicular to the arrangement direction. Such shifts in the light condensing positions of the light fluxes reduce the quality of illumination light and, for example, with a drawing apparatus that uses the light irradiation apparatus, reduce the accuracy of pattern drawing. Other light irradiation apparatuses using a lens array and a condenser system for overlapping the light fluxes from the lens array are also known from e.g. <CIT> or <CIT>. The apparatus of <CIT> thereby comprises a divergent lens in the condenser system for shortening the focal length of the system. An irradiation apparatus where the lens array is combined with another lens array for providing a beam width reduction telescope arrangement is known from <CIT>.

The present invention is intended for a light irradiation apparatus according to the independent claim <NUM> , and it is an object of the present invention to suppress shifts in the light condensing positions of a plurality of light fluxes on an irradiation plane.

A light irradiation apparatus according to the present invention includes a light source part for emitting laser light toward a predetermined position, and an irradiation optical system disposed at the predetermined position and for guiding the laser light from the light source part along an optical axis to an irradiation plane. The irradiation optical system includes a division lens part having a plurality of element lenses arranged in a first direction perpendicular to the optical axis, and for using the plurality of element lenses to divide incident light into a plurality of light fluxes, and a light condensing part disposed between the division lens part and the irradiation plane and for superimposing irradiation regions of the plurality of light fluxes on each other on the irradiation plane.

The irradiation optical system includes a plurality of transparent parts arranged in the first direction and having different optical path lengths and light fluxes that have passed through the plurality of element lenses or light fluxes that travel toward the plurality of element lenses are respectively incident on the plurality of transparent parts. The plurality of light fluxes enter the light condensing part as parallel light when viewed in the first direction, and the light condensing part causes the plurality of light fluxes to converge on the irradiation plane. The light condensing part includes a diverging part for causing the parallel light to diverge in the second direction, and a converging lens on which light from the diverging part is incident and that causes the light to converge on the irradiation plane when viewed in the first direction.

The above-described light irradiation apparatus can readily achieve a design in which the focal length of the light condensing part with respect to the second direction is reduced and consequently can suppress shifts in the light condensing positions of the plurality of light fluxes on the irradiation plane.

Preferably, the diverging part is a cylindrical lens having negative power in only the second direction.

The irradiation optical system further includes a width adjustment part for making a width, in the second direction, of the parallel light incident on the light condensing part smaller than a width, in the second direction, of the collimated laser light when viewed in the first direction.

Preferably, each of the plurality of element lenses of the division lens part has a spherical lens surface, and the lens surface serves as part of the width adjustment part.

The present invention is also intended for a drawing apparatus. The drawing apparatus according to the present invention includes the above-described light irradiation apparatus, a spatial light modulator disposed on the irradiation plane of the light irradiation apparatus, a projection optical system for guiding spatially modulated light emitted from the spatial light modulator onto an object, a movement mechanism for moving an irradiation position to be irradiated with the spatially modulated light on the object, and a control part for controlling the spatial light modulator in synchronization with the movement of the irradiation position by the movement mechanism.

<FIG> illustrates a configuration of a drawing apparatus <NUM>. The drawing apparatus <NUM> is a direct drawing apparatus for drawing a pattern by irradiating a surface of a substrate <NUM> such as a semiconductor substrate or a glass substrate, to which a photosensitive material is applied, with light beams. The drawing apparatus <NUM> includes a stage <NUM>, a movement mechanism <NUM>, a light irradiation apparatus <NUM>, a spatial light modulator <NUM>, a projection optical system <NUM>, and a control part <NUM>. The stage <NUM> holds the substrate <NUM>, and the movement mechanism <NUM> moves the stage <NUM> along a main surface of the substrate <NUM>. The movement mechanism <NUM> may rotate the substrate <NUM> about an axis perpendicular to the main surface.

The light irradiation apparatus <NUM> irradiates the spatial light modulator <NUM> with linear light (light having a linear cross section) via a mirror <NUM>. The details of the light irradiation apparatus <NUM> will be described later. The spatial light modulator <NUM> is of, for example, a diffraction grating type as well as a reflection type, and is a diffraction grating whose grating depth can be changed. The spatial light modulator <NUM> is manufactured using semiconductor device manufacturing technologies. The diffraction grating type light modulator used in the present embodiment is, for example, GLV (Grating Light Valve), which is a registered trademark of Silicon Light Machines, Sunnyvale, California. The spatial light modulator <NUM> includes a plurality of grating elements arranged in a row, and each grating element transitions between a state in which first-order diffraction light is emitted and a state in which zero-order diffraction light (zero-order light) is emitted. Thus, spatially modulated light is emitted from the spatial light modulator <NUM>.

The projection optical system <NUM> includes a douser <NUM>, a lens <NUM>, a lens <NUM>, an aperture plate <NUM>, and a focusing lens <NUM>. The douser <NUM> blocks off ghost light and part of high-order diffraction light, and passes the light emitted from the spatial light modulator <NUM>. The lenses <NUM> and <NUM> constitute a zoom part. The aperture plate <NUM> blocks off plus and minus first-order diffraction light (and high-order diffraction light), and passes zero-order diffraction light. The light that has passed through the aperture plate <NUM> is guided onto the main surface of the substrate <NUM> by the focusing lens <NUM>. In this way, the projection optical system <NUM> guides the spatially modulated light of the spatial light modulator <NUM> onto the substrate <NUM>.

The control part <NUM> is connected to and controls the light irradiation apparatus <NUM>, the spatial light modulator <NUM>, and the movement mechanism <NUM>. In the drawing apparatus <NUM>, the movement mechanism <NUM> moves the stage <NUM> to move an irradiation position to be irradiated with the light emitted from the spatial light modulator <NUM> on the substrate <NUM>. The control part <NUM> also controls the spatial light modulator <NUM> in synchronization with the movement of the irradiation position by the movement mechanism <NUM>. Accordingly, a desired pattern is drawn on the photosensitive material of the substrate <NUM>.

<FIG> and <FIG> illustrate a configuration of the light irradiation apparatus <NUM>. In <FIG> and <FIG>, a direction parallel to an optical axis J1 of an irradiation optical system <NUM>, which will be described later, is shown as a Z direction, and directions perpendicular to the Z direction and orthogonal to each other are shown as X and Y directions (the same applies below). <FIG> illustrates the configuration of the light irradiation apparatus <NUM> when viewed in (along) the Y direction, and <FIG> illustrates the configuration of the light irradiation apparatus <NUM> when viewed in the X direction.

The light irradiation apparatus <NUM> in <FIG> and <FIG> includes a light source unit <NUM> and the irradiation optical system <NUM>. The light source unit <NUM> includes a plurality of light source parts <NUM>, and each light source part <NUM> includes a single light source <NUM> (e.g., a semiconductor laser) and a single collimating lens <NUM>. The light sources <NUM> of the light source parts <NUM> are arranged in approximately the X direction on a plane (hereinafter, referred to as a "light source arrangement plane") parallel to a ZX plane. Laser light emitted from each light source <NUM> is collimated by the collimating lens <NUM> and enters the irradiation optical system <NUM>. In the light source unit <NUM>, the light source parts <NUM> arranged on the light source arrangement plane emit laser light from different directions along the light source arrangement plane toward the same position (a division lens part <NUM> described later) on the irradiation optical system <NUM>.

The irradiation optical system <NUM> is disposed at the irradiation position to be irradiated with the laser light emitted from the light source parts <NUM>. The irradiation optical system <NUM> guides the laser light along the optical axis J1 to the surface of the spatial light modulator <NUM>, which is an irradiation plane indicated by the broken line <NUM> in <FIG> and <FIG>, i.e., to the surfaces of the plurality of grating elements. In actuality, the light irradiation apparatus <NUM> includes the mirror <NUM> as a constituent element since, as described previously, the light from the light irradiation apparatus <NUM> is emitted onto the spatial light modulator <NUM> via the mirror <NUM>. However, for convenience of illustration, the mirror <NUM> is omitted from <FIG> and <FIG> (the same applies below).

The irradiation optical system <NUM> includes an optical path length difference generation part <NUM>, the division lens part <NUM>, and a light condensing part <NUM>. In the irradiation optical system <NUM>, the division lens part <NUM>, the optical path length difference generation part <NUM>, and the light condensing part <NUM> are arranged in this order along the optical axis J1 from the light source unit <NUM> toward the irradiation plane <NUM>. The collimated laser light from the light source parts <NUM> enters the division lens part <NUM>.

<FIG> is a partial enlarged view of the division lens part <NUM> and the optical path length difference generation part <NUM>. The division lens part <NUM> includes a plurality of lenses <NUM> (hereinafter, referred to as "element lenses <NUM>") that are densely arranged with a fixed pitch in a direction (here, the X direction) that is perpendicular to the optical axis J1 of the irradiation optical system <NUM> and along the light source arrangement plane. Each element lens <NUM> is in the shape of a block that is long in the Y direction, and has a first lens surface <NUM> that is a side surface on the -Z side (the light source unit <NUM> side) and a second lens surface <NUM> that is a side surface on the +Z side (the optical path length difference generation part <NUM> side). When viewed in the Y direction, the first lens surface <NUM> is a convex surface protruding on the -Z side, and the second lens surface <NUM> is a convex surface protruding on the +Z side. When viewed in the X direction, each element lens <NUM> has a rectangular shape (see <FIG>). In this way, the element lenses <NUM> are cylindrical lenses that have power in only the X direction, and the division lens part <NUM> is generally called a cylindrical lens array (or a cylindrical fly-eye lens).

The first lens surface <NUM> and the second lens surface <NUM> have a symmetrical shape relative to a plane perpendicular to the optical axis J1 (i.e., a plane parallel to an XY plane). The first lens surface <NUM> is arranged at the focal point of the second lens surface <NUM>, and the second lens surface <NUM> is arranged at the focal point of the first lens surface <NUM>. In other words, the first lens surface <NUM> and the second lens surface <NUM> have the same focal length. The parallel light incident on the element lenses <NUM> converges on the second lens surface <NUM>. The plurality of element lens <NUM> stacked in the X direction may be formed as an integral member, or may be separately formed and bonded together.

When viewed in the Y direction, the light incident on the division lens part <NUM> is divided in the X direction by the plurality of element lenses <NUM>. At this time, the parallel light from each light source part <NUM> enters the first lens surface <NUM> of each element lens <NUM> so that images of the plurality of light sources <NUM> are formed in the vicinity of the second lens surface <NUM>. The light (a plurality of light fluxes) divided by the element lenses <NUM> is emitted from the second lens surfaces <NUM> so that the principal rays are parallel to the optical axis J1 (Z direction). The light fluxes emitted from the respective element lenses <NUM> enter the optical path length difference generation part <NUM> while spreading out.

The optical path length difference generation part <NUM> includes a plurality of transparent parts <NUM> that are densely arranged with a fixed pitch in a direction (here, the X direction) that is perpendicular to the optical axis J1 and along the light source arrangement plane. In the example in <FIG>, the number of transparent parts <NUM> of the optical path length difference generation part <NUM> is smaller by one than the number of element lenses <NUM> of the division lens part <NUM>. The array pitch of the transparent parts <NUM> is equal to that of the element lenses <NUM>. Each transparent part <NUM> is (ideally) in the shape of a block that has surfaces perpendicular to the X, Y, and Z directions. The transparent parts <NUM> arranged in a row in the X direction have the same X-direction length and the same Y-direction length, but have different lengths in the Z direction, i.e., in the direction along the optical axis J1. Thus, the transparent parts <NUM> have different optical path lengths. In the optical path length difference generation part <NUM> in <FIG>, the transparent part <NUM> that is closer to the +X side among the plurality of transparent parts <NUM> has a smaller Z-direction length. The lengths of the transparent parts <NUM> in the direction of the optical axis J1 do not necessarily have to increase (or decrease) in order in the X direction, and may form a randomly irregular shape. In the present case, the transparent parts <NUM> of the optical path length difference generation part <NUM> are made of the same material, and formed as an integral member. Alternatively, the transparent parts <NUM> of the optical path length difference generation part <NUM> may be separately formed and bonded together.

The division lens part <NUM> and the optical path length difference generation part <NUM> are disposed close to each other in the Z direction, and the plurality of element lenses <NUM>, excluding the element lens <NUM> furthest to the +X side, and the plurality of transparent parts <NUM> are respectively arranged at the same position in the X direction. Thus, the light fluxes that have passed through these element lenses <NUM> respectively enter the transparent parts <NUM>. To be more specific, the light flux emitted from the second lens surface <NUM> (see <FIG>) of each element lens <NUM> enters an entrance surface <NUM>, which is the -Z side surface of the transparent part <NUM> disposed at the same position in the X direction. This light flux passes through the transparent part <NUM> and is emitted from an exit surface <NUM>, which is the +Z side surface of the transparent part <NUM>. Note that the light flux that has passed through the element lens <NUM> located furthest to the +X side does not pass through any of the transparent parts <NUM>.

In actuality, the width, in the X direction, of the light flux emitted from the exit surface <NUM> of each transparent part <NUM> becomes smaller than the width, in the X direction, of the transparent part <NUM>, i.e., the array pitch of the transparent part <NUM>. This prevents or suppresses the light flux from falling on the edges of the transparent part <NUM> (i.e., the edges in the X direction, principally the edges of the entrance surface <NUM> and the exit surface <NUM>). Note that the optical path length difference generation part <NUM> may include the same number of transparent parts <NUM> as the number of element lenses <NUM> of the division lens part <NUM>. In this case, the light fluxes that have passed through the plurality of (all) element lenses <NUM> will respectively enter the plurality of transparent parts <NUM>.

As illustrated in <FIG> and <FIG>, the light flux that has passed through each transparent part <NUM> travels toward the light condensing part <NUM>. The light condensing part <NUM> includes three cylindrical lenses <NUM>, <NUM>, and <NUM>. The cylindrical lens <NUM> has positive power in the X direction, which is the direction of arrangement of the element lens <NUM>, but does not have power in the Y direction, which is perpendicular to the optical axis J1 and the above arrangement direction. The cylindrical lens <NUM> is disposed at a position spaced on the +Z side by its focal length fC from the second lens surfaces <NUM> of the element lenses <NUM>. In other words, the second lens surface <NUM> of each element lens <NUM> is disposed at a front focal position (front focal point) of the cylindrical lens <NUM>. The irradiation plane <NUM> on the optical axis J1 is disposed at a position spaced on the +Z side by the focal length fC of the cylindrical lens <NUM> from the cylindrical lens <NUM>. In other words, the irradiation plane <NUM> is disposed at a back focal position of the cylindrical lens <NUM>.

The cylindrical lens <NUM> has negative power in the Y direction, but does not have power in the X direction. The cylindrical lens <NUM> is disposed between the optical path length difference generation part <NUM> and the cylindrical lens <NUM>. The cylindrical lens <NUM> has positive power in the Y direction, but does not have power in the X direction. The cylindrical lens <NUM> is disposed between the cylindrical lens <NUM> and the irradiation plane <NUM>. As will be described later, when viewed in the X direction, the cylindrical lens <NUM> causes the incident light to diverge, and the cylindrical lens <NUM> cause the incident light to converge. Hereinafter, the cylindrical lens <NUM> is referred to as the "diverging lens <NUM>," and the cylindrical lens <NUM> is referred to as the "converging lens <NUM>.

Among the plurality of optical elements of the irradiation optical system <NUM>, the converging lens <NUM>, which is closest to the irradiation plane <NUM>, is disposed at a position spaced on the -Z side by a predetermined distance fb (hereinafter, referred to as a "back focus fb") from the irradiation plane <NUM>. When considering only the Y direction, a composite focal length (combined focal length) fL resulting from the diverging lens <NUM> and the converging lens <NUM> is shorter than the back focus fb. The composite focal length fL can be regarded as the focal length of the light condensing part <NUM> when considering only the Y direction, and is referred to as the "focal length fL of the light condensing part <NUM> with respect to the Y direction" in the following description.

Here, the focal length fL of the light condensing part <NUM> with respect to the Y direction can be expressed by Expression <NUM>, where fL1 is the focal length of the diverging lens <NUM>, fL2 is the focal length of the converging lens <NUM>, and dL is the distance between the diverging lens <NUM> and the converging lens <NUM>. Similarly, the back focus fb can be expressed by Expression <NUM>. Note that the thickness of each lens is disregarded in Expressions <NUM> and <NUM>. <MAT><MAT>.

As is clear from Expressions <NUM> and <NUM>, the focal length fL of the light condensing part <NUM> with respect to the Y direction and the back focus tb are determined by only the focal length fL1 of the diverging lens <NUM>, the focal length fL2 of the converging lens <NUM>, and the distance dL between the two lenses.

When viewed in the Y direction as illustrated in <FIG>, the light fluxes emitted from the element lenses <NUM> are collimated by the cylindrical lens <NUM> and superimposed on one another on the irradiation plane <NUM>. In other words, irradiation regions <NUM> of the light emitted from the element lens <NUM> (i.e., the plurality of light fluxes that have passed through the transparent parts <NUM>) wholly overlap. The irradiation regions <NUM> are indicated by a bold solid line in <FIG> and <FIG> and have a fixed width in the X direction. As described previously, the light fluxes emitted from the element lens <NUM> pass through the different transparent parts <NUM>. This produces differences between the optical path lengths of the light fluxes that travel from the division lens part <NUM> to the irradiation plane <NUM>, thus suppressing (or preventing) the appearance of interference fringes in the irradiation plane <NUM> due to the interference of the light divided by the element lenses <NUM>. In other words, the intensity distribution, in the X direction, of light on the irradiation plane <NUM> becomes approximately uniform as illustrated in the upper section of <FIG>. For each combination of two transparent parts <NUM> out of the plurality of transparent parts <NUM>, a difference between the optical path lengths of the light fluxes that have passed through the two transparent parts <NUM> is preferably greater than or equal to the coherence length of the laser light emitted from the light source part <NUM>.

When viewed in the X direction as illustrated in <FIG>, the light incident on the division lens part <NUM> from the light source unit <NUM> passes as parallel light along the optical axis J1 (precisely, parallel light that is parallel to a ZX plane) through the division lens part <NUM> and the optical path length difference generation part <NUM> and is guided to the diverging lens <NUM>. The diverging lens <NUM>, which has negative power in only the Y direction, causes this parallel light to diverge in the Y direction. The divergent light from the diverging lens <NUM> passes through the cylindrical lens <NUM> and enters the converging lens <NUM>. The converging lens <NUM>, which has positive power in only the Y direction, causes the divergent light from the diverging lens <NUM> to converge on the irradiation plane <NUM>. Thus, the irradiation region <NUM> of the light from each element lens <NUM> forms a line that extends in the X direction on the irradiation plane <NUM>. This obtains linear illumination light that is the collection of the light fluxes that have passed through the element lenses <NUM> and whose cross section on the irradiation plane <NUM> (i.e., cross section of light fluxes that is perpendicular to the optical axis J1; the same applies below) forms a line that extends in the X direction. The intensity distribution, in the Y direction, of the linear illumination light is illustrated in the lower section of <FIG>.

Now, a light irradiation apparatus according to a comparative example will be described. <FIG> and <FIG> illustrate a configuration of a light irradiation apparatus <NUM> according to a comparative example The light irradiation apparatus <NUM> of the comparative example includes a light source part <NUM>, a division lens part <NUM>, an optical path length difference generation part <NUM>, and a light condensing part <NUM>. The configurations of the light source part <NUM>, the division lens part <NUM>, and the optical path length difference generation part <NUM> are the same as those of the light irradiation apparatus <NUM> in <FIG> and <FIG>. The light condensing part <NUM> includes two cylindrical lenses <NUM> and <NUM>. The position of the cylindrical lens <NUM> relative to the irradiation plane <NUM> is the same as that of the cylindrical lens <NUM> in <FIG> and <FIG>. On the other hand, the cylindrical lens <NUM>, which is closest to the irradiation plane <NUM>, is disposed at a position on the -Z side by its focal length fr from the irradiation plane <NUM>. The focal length fr of the cylindrical lens <NUM> is the focal length of the light condensing part <NUM> with respect to the Y direction.

As illustrated in <FIG>, manufacturing limitations of the element lenses <NUM> of the division lens part <NUM> result in the angles αh (also referred to as "wedge angles" and hereinafter also referred to as "parallelisms") of the second lens surfaces <NUM> relative to the first lens surfaces <NUM> when viewed in the X direction not being zero, and the parallelism being different for each element lens <NUM>. Similarly, manufacturing limitations of the transparent parts <NUM> of the optical path length difference generation part <NUM> result in the angles αs of the exit surfaces <NUM> relative to the entrance surfaces <NUM> when viewed in the X direction not being zero, and the parallelism being different for each transparent part <NUM>. Although the parallelism can be controlled to be in the range of several seconds to several tens of seconds by manufacturing the division lens part <NUM> and the optical path length difference generation part <NUM> with higher accuracy, the manufacturing costs of the division lens part <NUM> and the optical path length difference generation part <NUM> will increase. For convenience of illustration, <FIG> illustrates the division lens part <NUM> and the optical path length difference generation part <NUM> as being spaced from each other in the Z direction.

In the example in <FIG>, when viewed in the X direction, the travel direction of the light emitted from the second lens surface <NUM> of the element lens <NUM> is inclined by an angle θh to the travel direction of the light incident on the first lens surface <NUM>, which is assumed to be parallel to a ZX plane, and the travel direction of the light emitted from the exit surface <NUM> of the transparent part <NUM> is inclined by an angle θs to the travel direction of the light incident on the entrance surface <NUM>. Thus, the travel direction of the light that has passed through the element lens <NUM> and the transparent part <NUM> is inclined by an angle θy (θy = θh + θs) to the travel direction of the light incident on the first lens surface <NUM> of the element lens <NUM>, i.e., to the optical axis J1. The above angle θh is expressed as (nh - <NUM>)αh, where nh is the refractive index of the element lens <NUM>, and the above angle θs is expressed as (ns - <NUM>)αs, where ns is the refractive index of the transparent part <NUM>. Note that the refractive index of air is assumed to be <NUM>, and the angles αh, αs, θh, and θs are assumed to be sufficiently small.

In the light irradiation apparatus <NUM> of the comparative example in <FIG>, when a plurality of light fluxes that respectively have passed through the plurality of element lenses <NUM> enter the light condensing part <NUM> at different angles θy1 and θy2 relative to the optical axis J1 due to variations of the parallelisms of the element lenses <NUM> and the transparent parts <NUM> as illustrated in <FIG>, the light condensing positions of the plurality of light fluxes on the irradiation plane <NUM> are shifted from one another in the Y direction. In <FIG>, the distances of the light condensing positions of the light fluxes from the optical axis J1 are indicated by Δy1 and Δy2. Such shifts in the light condensing positions of the light fluxes increase the width in the Y direction of the linear illumination light, which is the collection of the light fluxes, on the irradiation plane <NUM>. In actuality, the profile of the intensity distribution, in the Y direction, of the linear illumination light becomes deformed as illustrated in <FIG> as compared with that of the intensity distribution in the lower section of <FIG>.

Here, the distance Δy, in the Y direction, of the light condensing position of each light flux from the optical axis J1 on the irradiation plane <NUM> (hereinafter simply referred to as the "shift amount of the light condensing position") can be expressed by Expression <NUM>, using the angle θy (hereinafter, referred to as the "incident angle in the light condensing part") of the travel direction of the light flux incident on the light condensing part <NUM> relative to the optical axis J1, and the focal length fr of the light condensing part <NUM> with respect to the Y direction. In Expression <NUM>, the incident angle θy in the light condensing part is assumed to be sufficiently small.

By reducing the shift amounts Δy of the light condensing positions of the plurality of light fluxes, it is possible to suppress deformation of the profile of the intensity distribution, in the Y direction, of the linear illumination light. As can be seen from Expression <NUM>, the shift amount Δy of the light condensing position can be expressed as the product of the focal length fr of the light condensing part <NUM> with respect to the Y direction and the incident angle θy in the light condensing part. Thus, the shift amount Δy of the light condensing position can be reduced by reducing at least one of the focal length fr of the light condensing part <NUM> with respect to the Y direction and the incident angle θy in the light condensing part.

In the light irradiation apparatus <NUM> illustrated in <FIG> and <FIG>, the light condensing part <NUM> includes the diverging lens <NUM> for causing light fluxes incident as parallel light when viewed in the X direction to diverge in the Y direction, and the converging lens <NUM> for causing the light from the diverging lens <NUM> to converge on the irradiation plane <NUM>. This configuration allows the focal length fL, of the light condensing part <NUM> with respect to the Y direction to be shorter than the focal length fr of the light condensing part <NUM> with respect to the Y direction according to the comparative example, even when the back focus fb is equal to or longer than that of the light irradiation apparatus <NUM> of the comparative example. In other words, a design can be readily achieved in which the focal length fL of the light condensing part <NUM> with respect to the Y direction is reduced while the back focus fb is relatively long. Consequently, it is possible to suppress shifts in the light condensing positions of the plurality of light fluxes on the irradiation plane <NUM> due to variations of the parallelisms of the element lenses <NUM> and the parallelisms of the transparent parts <NUM>, and to thereby irradiate the irradiation plane <NUM> with preferable linear illumination light. In addition, high-accuracy pattern drawing is possible with the drawing apparatus <NUM> including the light irradiation apparatus <NUM>. Note that the light irradiation apparatus <NUM> can be regarded as being obtained by replacing the cylindrical lens <NUM> of the light condensing part <NUM> of the comparative example with the two cylindrical lenses <NUM> and <NUM>.

The light irradiation apparatus <NUM> in <FIG> emits laser light from the plurality of light source parts <NUM> toward the division lens part <NUM>. This produces higher-strength (intensity) linear illumination light than in the light irradiation apparatus <NUM> of the comparative example that uses only a single light source part <NUM>.

Incidentally, the light irradiation apparatus <NUM> in <FIG> and <FIG> will have higher numerical aperture (NA) on the image side than the light irradiation apparatus <NUM> of the comparative example when the back focus fb is equal to that in the light irradiation apparatus <NUM> of the comparative example. Next is a description of a light irradiation apparatus <NUM> in which the focal length of the light condensing part <NUM> with respect to the Y direction is shorter than that in the light irradiation apparatus <NUM> of the comparative example while NA on the image side is the same as that in the light irradiation apparatus <NUM> of the comparative example.

<FIG> show another example of the light irradiation apparatus <NUM>. <FIG> illustrates a configuration of the light irradiation apparatus <NUM> when viewed in the Y direction, and <FIG> illustrates the configuration of the light irradiation apparatus <NUM> when viewed in the X direction. The light irradiation apparatus <NUM> in <FIG> differs from that in <FIG> and <FIG> in that the diverging lens <NUM> is omitted, and a width adjustment part <NUM> is added to the irradiation optical system <NUM>. The other constituent elements are the same as those of the light irradiation apparatus <NUM> in <FIG> and <FIG>, and the same constituent elements are denoted by the same reference numerals.

As illustrated in <FIG>, the width adjustment part <NUM> is provided between the light source unit <NUM> and the division lens part <NUM>. The width adjustment part <NUM> is a beam expander for changing the width, in the Y-direction, of incident laser light, and includes two cylindrical lenses <NUM> and <NUM>. The two cylindrical lenses <NUM> and <NUM> both have positive power in the Y direction, but do not have power in the X direction. A distance de between the two cylindrical lenses <NUM> and <NUM> can be expressed as (fe1 + fe2), where fe1 is the focal length of the cylindrical lens <NUM> and fe2 is the focal length of the cylindrical lens <NUM>. The focal length fe1 of the cylindrical lens <NUM> disposed on the light source unit <NUM> side is greater than the focal length fe2 of the cylindrical lens <NUM> disposed on the division lens part <NUM> side.

As described previously, collimated laser light is incident on the irradiation optical system <NUM> from each light source part <NUM>. In the irradiation optical system <NUM>, the width adjustment part <NUM> is disposed furthest to the light source unit <NUM> side, and the collimated laser light enters the cylindrical lens <NUM> of the width adjustment part <NUM>. At this time, when viewed in the X direction as illustrated in <FIG>, the laser light enters the cylindrical lens <NUM> as parallel light along the optical axis J1 (more precisely, parallel light that is parallel to a ZX plane) and is emitted from the cylindrical lens <NUM> as parallel light along the optical axis J1. The width, in the Y direction, of the parallel light emitted from the cylindrical lens <NUM> is smaller than the width, in the Y direction, of the parallel light incident on the cylindrical lens <NUM>.

The parallel light that has passed through the width adjustment part <NUM> passes through the division lens part <NUM>, the optical path length difference generation part <NUM>, and the cylindrical lens <NUM> of the light condensing part <NUM> without being subject to a lens function in the Y direction, and then enters the converging lens <NUM>. The converging lens <NUM> causes this parallel light to converge in the Y direction and to condense on the irradiation plane <NUM>. Note that the optical path when viewed in the Y direction is the same as that in the light irradiation apparatus <NUM> in <FIG>.

As described above, the light irradiation apparatus <NUM> in <FIG> includes the width adjustment part <NUM> for changing the beam width in only the Y direction so that, when viewed in the Y direction, the width, in the Y direction, of the parallel light incident on the light condensing part <NUM> becomes smaller than the width, in the Y direction, of the laser light incident on the irradiation optical system <NUM> from the light source part <NUM>.

It is assumed here that the NA on the image side of the light irradiation apparatus <NUM> in <FIG> is equal to that of the light irradiation apparatus <NUM> of the comparative example in <FIG>. In this case, the focal length fL of the light condensing part <NUM> with respect to the Y direction (here, the focal length of the converging lens <NUM>) is expressed as M times the focal length fr of the light condensing part <NUM> with respect to the Y direction according to the comparative example, where M is the reduction ratio in the Y direction of the width adjustment part <NUM> (M is less than one). In other words, the focal length fL of the light condensing part <NUM> with respect to the Y direction is shorter than the focal length fr of the light condensing part <NUM> with respect to the Y direction. Note that the reduction ratio M in the Y direction of the width adjustment part <NUM> depends on the focal lengths fe1 and fe2 of the cylindrical lenses <NUM> and <NUM>.

Thus, the light irradiation apparatus <NUM> in <FIG> can readily achieve a design in which the focal length of the light condensing part <NUM> with respect to the Y direction is reduced while the NA on the image side is equal to that of the light irradiation apparatus <NUM> of the comparative example. Consequently, it is possible to suppress the shift (shift in the Y direction) in the light condensing positions of the plurality of light fluxes on the irradiation plane <NUM>.

Alternatively, the light irradiation apparatus <NUM> in <FIG> may include the width adjustment part <NUM> for each of the plurality of light source parts <NUM>. In this case, the cylindrical lenses <NUM> and <NUM> can be replaced with two lenses that have power in both of the X and Y directions. The two lenses of such a width adjustment part <NUM> constitute a double (both side) telecentric optical system. As another alternative, the cylindrical lenses <NUM> and <NUM> of the width adjustment part <NUM> may be provided between the optical path length difference generation part <NUM> and the cylindrical lens <NUM>. These variations are also possible with other light irradiation apparatuses <NUM> including the width adjustment part <NUM>.

The light irradiation apparatus <NUM> may implement part of the function of the width adjustment part <NUM> with a division lens part. More specifically, as illustrated in <FIG>, both of the first lens surface <NUM> and the second lens surface <NUM> of each element lens 620a of a division lens part 62a form part of spherical surfaces, and the cylindrical lens <NUM> of the light irradiation apparatus <NUM> in <FIG> is omitted. Moreover, the first lens surfaces <NUM> of the element lenses 620a are disposed at a position spaced by the focal length fe1 of the cylindrical lens <NUM> from the cylindrical lens <NUM>. In the division lens part 62a as well, the first lens surface <NUM> of each element lens 620a is disposed at the focal point of the second lens surface <NUM>, and the second lens surface <NUM> is disposed at the focal point of the first lens surface <NUM>. In other words, the first lens surface <NUM> and the second lens surface <NUM> have the same focal length.

When viewed in the X direction, the laser light from the light source parts <NUM> enters the cylindrical lens <NUM> as parallel light along the optical axis J1 (more precisely, parallel light that is parallel to a ZX plane). The light emitted from cylindrical lens <NUM> converges on the first lens surfaces <NUM> of the element lenses 620a and travels toward the second lens surfaces <NUM> while spreading out within the element lenses 620a. Then, parallel light is emitted along the optical axis J1 from the second lens surfaces <NUM>. The width, in the Y direction, of the parallel light emitted from the element lenses 620a is smaller than the width, in the Y direction, of the parallel light incident on the cylindrical lens <NUM>. The parallel light emitted from the element lenses 620a enters the converging lens <NUM> via the optical path length difference generation part <NUM> and the cylindrical lens <NUM> and converges on the irradiation plane <NUM>.

As described above, the light irradiation apparatus <NUM> in <FIG> is configured such that each element lens 620a of the division lens part 62a has a spherical surface as the second lens surface <NUM>, and the second lens surfaces <NUM> serve as part of the width adjustment part <NUM>. This configuration allows parallel light having a small width in the Y direction (parallel light when viewed in the X direction) to be incident on the light condensing part <NUM> disposed between the division lens part 62a and the irradiation plane <NUM>, and therefore can readily reduce the focal length fL of the light condensing part <NUM> with respect to the Y direction. It is also possible to reduce the number of constituent elements as compared to the light irradiation apparatus <NUM> in <FIG>.

Incidentally, for each element lens 620a having spherical surfaces as its first and second lens surfaces <NUM> and <NUM>, a center line C1 of the element lens 620a may be shifted from an optical axis J2 that passes through the focal point of the element lens 620a due to errors in manufacture as illustrated in <FIG> (this phenomenon can also be regarded as "decentering"). When viewed in the X direction, if such an element lens 620a is disposed such that its center line C1 matches the optical axis J1 of the irradiation optical system <NUM>, a path K1 of light incident along the optical axis J1 will be inclined relative to the optical axis <NUM>. In this case, the light condensing position of the light flux on the irradiation plane <NUM> is shifted in the Y direction from the optical axis J1 and accordingly the profile of the intensity distribution, in the Y direction, of the linear illumination light becomes deformed, as in the case where the parallelism of the element lens <NUM> serving as a cylindrical lens decreases.

On the other hand, in a light irradiation apparatus <NUM>, the position of each element lens 620a is adjusted in the manufacture of the division lens part 62a such that the optical axis J2 rather than the center line C1 of the element lens 620a matches the optical axis J1 of the irradiation optical system <NUM> as illustrated in <FIG>. This reduces the possibility that the light condensing positions of the light fluxes that have passed through the element lenses 620a may be shifted in the Y direction from the optical axis J1 on the irradiation plane <NUM>. The light irradiation apparatus <NUM> including such a division lens part 62a can limit the factors that cause shifts in the light condensing positions of light fluxes on the irradiation plane <NUM> to variation in the parallelism of the transparent parts <NUM> and therefore can further suppress shifts in the light condensing positions of light fluxes on the irradiation plane <NUM>.

The light irradiation apparatus <NUM> may also be configured such that the first lens surfaces <NUM> of the element lenses 620a serve as part of the width adjustment part <NUM>. In this case, the cylindrical lens <NUM> is provided on the +Z side of the element lens 620a. When viewed in the X direction, the parallel light incident on the first lens surfaces <NUM> of the element lenses 620a converges on the second lens surfaces <NUM>. The light emitted from the second lens surfaces <NUM> is collimated by the cylindrical lens <NUM> and enters the light condensing part <NUM>. At this time, the width, in the Y direction, of the parallel light incident on the light condensing part <NUM> becomes smaller than the width, in the Y direction, of the laser light incident on the irradiation optical system <NUM> from the light source part <NUM> like the above.

The light irradiation apparatus <NUM> in <FIG> can make the NA on the image side equal to that in the light irradiation apparatus <NUM> of the comparative example, but in this case, the back focus becomes shorter than that in the light irradiation apparatus <NUM> of the comparative example. Next is a description of a light irradiation apparatus <NUM> that can make the focal length of the light condensing part <NUM> with respect to the Y direction shorter than that in the light irradiation apparatus <NUM> of the comparative example while having the same back focus and the same NA on the image side as in the light irradiation apparatus <NUM> of the comparative example.

<FIG> shows another example of the light irradiation apparatus <NUM> and illustrates a configuration of the light irradiation apparatus <NUM> when viewed in the X direction. The light irradiation apparatus <NUM> in <FIG> is obtained by adding the width adjustment part <NUM> in <FIG> to the light irradiation apparatus <NUM> in <FIG>. By adjusting the reduction ratio of the width adjustment part <NUM> and the focal lengths and arrangement of the diverging lens <NUM> and the converging lens <NUM>, the light irradiation apparatus <NUM> can make the focal length fL of the light condensing part <NUM> with respect to the Y direction shorter than in the light irradiation apparatus <NUM> of the comparative example, while having the same back focus fb and the same NA on the image side as in the light irradiation apparatus <NUM> of the comparative example. Consequently, it is possible to suppress shifts in the light condensing positions of a plurality of light fluxes on the irradiation plane <NUM>. In addition, the drawing apparatus including the light irradiation apparatus <NUM> of the comparative example can be modified by simply replacing the light irradiation apparatus <NUM> of the comparative example with the light irradiation apparatus <NUM> in <FIG> to achieve high-precision pattern drawing without significantly changing the design of the drawing apparatus, for example (the same applies to a light irradiation apparatus <NUM> in <FIG> and <FIG>, which will be described below).

<FIG> and <FIG> show another example of the light irradiation apparatus <NUM>. <FIG> illustrates a configuration of the light irradiation apparatus <NUM> when viewed in the Y direction, and <FIG> illustrates the configuration of the light irradiation apparatus <NUM> when viewed in the X direction. The light irradiation apparatus <NUM> in <FIG> and <FIG> is obtained by adding the diverging lens <NUM> in <FIG> to the light irradiation apparatus <NUM> in <FIG>. This configuration allows the focal length fL of the light condensing part <NUM> with respect to the Y direction to be shorter than that in the light irradiation apparatus <NUM> of the comparative example while having the same back focus fb and the same NA on the image side as in the light irradiation apparatus <NUM> of the comparative example, similarly to the case of the light irradiation apparatus <NUM> in <FIG>. It is also possible to reduce the number of constituent elements as compared to the light irradiation apparatus <NUM> in <FIG>. Alternatively, the cylindrical lens <NUM> of the width adjustment part <NUM> may be provided individually for each of a plurality of light source parts <NUM>.

The above-described light irradiation apparatuses <NUM> can be modified in various ways.

The division lens part <NUM> or 62a does not necessarily have to have a plurality of element lenses <NUM> or 620a arranged with a fixed pitch in the arrangement direction. For example, the element lenses <NUM> or 620a may have different widths in the arrangement direction. In this case, the widths, in the arrangement direction, of the plurality of transparent parts <NUM> of the optical path length difference generation part <NUM> are also changed so that every transparent part <NUM> has the same ratio of the width of the transparent part <NUM> to the width of the element lens <NUM> or 620a of the division lens part <NUM> or 62a corresponding to this transparent part <NUM> in the arrangement direction.

The optical path length difference generation part <NUM> does not necessarily have to be disposed adjacent to the division lens part <NUM>. For example, lenses <NUM> and <NUM> may be provided between the division lens part <NUM> and the optical path length difference generation part <NUM> as illustrated in <FIG>. The lenses <NUM> and <NUM> constitute a double telecentric optical system, so that a plurality of light fluxes that have passed through the plurality of element lenses <NUM> of the division lens part <NUM> respectively enter the plurality of transparent parts <NUM> of the optical path length difference generation part <NUM> via the lenses <NUM> and <NUM>.

When the light source unit <NUM> includes only a single light source part <NUM>, the optical path length difference generation part <NUM> may be disposed between the light source part <NUM> and the division lens part <NUM> as illustrated in <FIG>. However, this is not according to the invention. The light irradiation apparatus <NUM> in <FIG> includes lenses <NUM> and <NUM>, which constitute a double telecentric optical system, between the light source part <NUM> and the optical path length difference generation part <NUM>, and also includes lenses <NUM> and <NUM>, which constitute a double telecentric optical system, between the optical path length difference generation part <NUM> and the division lens part <NUM>. A plurality of light fluxes that have passed through the plurality of transparent parts <NUM> of the optical path length difference generation part <NUM> pass through the lenses <NUM> and <NUM> and respectively enter the plurality of element lenses <NUM> of the division lens part <NUM>. In other words, the light fluxes traveling toward the plurality of element lenses <NUM> respectively enter the plurality of transparent parts <NUM>. The provision of the diverging lens <NUM> and the converging lens <NUM> allows the light irradiation apparatuses <NUM> in <FIG> and <FIG> to readily achieve a design in which the focal length of the light condensing part <NUM> with respect to the Y direction is reduced. It is, of course, possible to provide the width adjustment part <NUM> in the light irradiation apparatuses <NUM> in <FIG> and <FIG>.

Depending on the uniformity of the linear illumination light required in the light irradiation apparatus <NUM>, the optical path length difference generation part <NUM> may be omitted. In this case as well, the above-described technique of reducing the focal length of the light condensing part <NUM> with respect to the Y direction is applied because the parallelism of the entrance and exit surfaces of the element lens <NUM> of the division lens part <NUM> varies among the element lenses <NUM> when the element lenses <NUM> are cylindrical lenses. As described above, the light irradiation apparatus <NUM> adopts the above-described technique of reducing the focal length of the light condensing part <NUM> with respect to the Y direction when a plurality of element lenses are a plurality of cylindrical lenses that do not have power in the Y direction or when the irradiation optical system <NUM> includes a plurality of transparent parts arranged in the X direction and having different optical path lengths (including a case where a plurality of element lenses are a plurality of cylindrical lenses and the irradiation optical system <NUM> includes a plurality of transparent parts). Note that when a plurality of transparent parts is provided in the apparatus, light fluxes that have passed through a plurality of element lenses or light fluxes that travel toward the element lenses will respectively enter the plurality of transparent parts.

Depending on the design of the light irradiation apparatus <NUM>, the converging lens <NUM> may be a spherical lens. In this case, the cylindrical lens <NUM> and the converging lens <NUM> cooperate to superimpose the irradiation regions <NUM> of a plurality of light fluxes on one another on the irradiation plane <NUM>. For the same reason, the lens <NUM> may be a spherical lens. In this case, the lenses <NUM> and <NUM> cooperate to cause the light to converge in the Y direction. The composite focal length fL is expressed as a combination of the three lenses <NUM>, <NUM>, and <NUM>. While the diverging part for causing parallel light to diverge in the Y direction is implemented by the diverging lens <NUM> having negative power in only the Y direction in the above-described embodiment, a lens having positive power may be provided as a diverging part. In this case as well, the focal length of the light condensing part <NUM> with respect to the Y direction can be reduced because light that has passed through the lens converges and then diverges in the Y direction. The diverging part may also be implemented by a different optical element such as a cylindrical mirror.

In the drawing apparatus <NUM>, the spatial light modulator <NUM> disposed on the irradiation plane <NUM> of the light irradiation apparatus <NUM> may be a device other than a diffraction grating type light modulator. For example, a spatial light modulator using a group of minute mirrors may be used.

The movement mechanism for moving the irradiation position of light on the substrate <NUM> may be a different mechanism other than the movement mechanism <NUM> for moving the stage <NUM>, and may, for example, be a movement mechanism for moving a head that includes the light irradiation apparatus <NUM>, the spatial light modulator <NUM>, and the projection optical system <NUM> relative to the substrate <NUM>.

An object on which the drawing apparatus <NUM> draws a pattern may be a substrate other than a semiconductor substrate or a glass substrate, and may be components other than substrates. The light irradiation apparatus <NUM> may be used in apparatuses other than the drawing apparatus <NUM>.

Claim 1:
A light irradiation apparatus (<NUM>) comprising:
a light source part (<NUM>) for emitting laser light toward a predetermined position; and
an irradiation optical system (<NUM>) disposed at said predetermined position and for guiding the laser light from said light source part along an optical axis (J1) to an irradiation plane (<NUM>),
wherein said irradiation optical system includes:
a division lens part (<NUM>, 62a) having a plurality of element lenses (<NUM>, 620a) arranged in a first direction perpendicular to said optical axis, and for using said plurality of element lenses to divide incident light into a plurality of light fluxes;
an optical path length difference generation part (<NUM>) including a plurality of transparent parts (<NUM>) arranged in said first direction, said plurality of transparent parts having different optical path lengths, light fluxes that have passed through said plurality of element lenses being respectively incident on said plurality of transparent parts; and
a light condensing part (<NUM>) disposed between said optical path length difference generation part and said irradiation plane and for superimposing irradiation regions (<NUM>) of said plurality of light fluxes on each other on said irradiation plane,
wherein
said plurality of light fluxes passing through said optical path length difference generation part enter said light condensing part as parallel light when viewed in said first direction, and said light condensing part causes said plurality of light fluxes to converge on said irradiation plane,
said light condensing part includes:
a diverging part (<NUM>) for causing said parallel light to diverge in a second direction perpendicular to said optical axis and said first direction; and
a converging lens (<NUM>) on which light from said diverging part is incident and that causes said light to converge on said irradiation plane when viewed in said first direction, wherein
each of said irradiation regions forms a line extending in said first direction on said irradiation plane,
collimated laser light is incident on said irradiation optical system from said light source part, and
said irradiation optical system further includes a width adjustment part (<NUM>) for making a width, in said second direction, of said parallel light incident on said light condensing part smaller than a width, in said second direction, of said collimated laser light when viewed in said first direction.