JPH0936026A - Projection aligner and manufacturing method of semiconductor device using the same apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the telecentric degree so as to uniformly illuminate the surface of a work, using an illuminating system including an optical integrator as a secondary optical source forming means by using an appropriately set light quantity control means for a part of the illuminating system. SOLUTION: Zoom lens 5 forms the image of an emitting part formed near a second focus 4 on an incident plane of an optical integrator through a light quantity control means 17. The integrator 6 has a plurality of microlenses, each having a tetragonal cross section, arranged two-dimensionally at specified pitch and secondary optical source is formed near its emission plane 6b. When this source is used for illuminating a masking plate 10 as a surface to be irradiated, the control means 17 used in a part of an illumination system is moved on the optical axis to adjust the brightness distribution on the masking plate 10, based on signals from brightness distribution measuring means. Thus, the plate can be uniformly illuminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus and a semiconductor device manufacturing method using the same, and more specifically to I
In a so-called stepper, which is a manufacturing device for semiconductor devices such as C, LSI, magnetic heads, and liquid crystal panels, a pattern on the reticle surface, which is a surface to be illuminated, is illuminated with a light flux having an appropriate illuminance distribution so that high resolution can be easily obtained. It is the one.

[0002]

2. Description of the Related Art In recent semiconductor device manufacturing technology, the resolution pattern line width is, for example, 1 μm as electronic circuits are highly integrated.
Since this is less than or equal to m, there is a demand for an optical projection exposure apparatus having a higher resolution than the conventional one.

Generally, when a circuit pattern on a reticle surface is projected onto a wafer surface (projection surface) via a projection optical system, the resolution line width of the circuit pattern depends on the wavelength used and the N.V. of the projection optical system. A
In addition to the above, the quality of the uniformity of the illuminance distribution on the projection surface has a great influence. Therefore, in many conventional projection exposure apparatuses, for example, an illuminometer is arranged on the surface of an XY stage on which a wafer is placed to measure the illuminance distribution on the projection surface.

For example, (b) an illuminance meter is attached to a part of an XY stage on which a wafer is placed, and the illuminance meter on the XY stage is moved onto a projection surface as necessary to measure the illuminance distribution. Method. (B) A method in which an illuminance meter is placed each time measurement is performed on a part of the XY stage surface, and the illuminance distribution in the projection plane is measured while moving the XY stage. Etc. are used.

In addition to this, in the illumination system of the recent projection exposure apparatus, for example, the distortion is adjusted by a condenser lens so that the illuminance distribution on the surface to be illuminated is made uniform. In Japanese Patent No. 42821, a light blocking member is arranged on the entrance surface of a microlens group of an optical integrator that constitutes an illumination system, and the illuminance distribution on the illuminated surface is corrected to make it uniform.

[0006]

However, in the method disclosed in Japanese Patent Laid-Open No. 64-42821, only two light-shielding members are provided so as to correspond to two microlenses.
The angle of incidence of the illumination light beam on the reticle surface deviates substantially from the design value, and the telecentricity (the angle of incidence of the imaging light beam to the normal vertical incidence) deviates on the image plane, thus degrading the imaging performance.

According to the present invention, when an illumination system including an optical integrator is used as a secondary light source forming unit to illuminate a surface to be illuminated, a properly set light amount control unit is used as a part of the illumination system to shift the telecentricity. Of a projection exposure apparatus and a semiconductor device manufacturing method using the projection exposure apparatus capable of easily exposing and irradiating a surface to be illuminated with various patterns and easily exposing and transferring various patterns on a reticle surface with high resolution. For the purpose of provision.

[0008]

A projection exposure apparatus according to the present invention comprises: (1-1) an illumination system having an optical integrator composed of a plurality of microlenses forming a secondary light source for a light beam from a light source on an illuminated surface. When illuminating the pattern of, and projecting the pattern on the substrate surface by the projection optical system to expose,
In the illumination system, a light amount control means for controlling the amount of light passing through at least one microlens of the plurality of microlenses of the optical integrator is provided on the light incident side of the optical integrator in the center of the optical integrator or in the center of the optical integrator. It is characterized in that it is provided in at least one of the four minute lenses which are rotationally symmetric and are located at the apexes of the square.

In particular, (1-1-1) the light quantity adjusting section for controlling the quantity of transmitted light of the light quantity control means comprises an ND filter or a light shielding member, (1-1-2) the light quantity control means Is axially movable, and is located at a predetermined distance from a surface optically conjugate with the irradiated surface,
(1-1-3) The light amount control means has a plurality of types of optical filters or light blocking members having different transmittances and transmission shapes, one of which is selected and inserted into or removed from the optical path. There is.

According to the method of manufacturing a semiconductor element of the present invention, (2-1) a pattern on a reticle surface is illuminated by an illumination system having an optical integrator composed of a plurality of microlenses forming a secondary light source with a light beam from a light source. When the semiconductor device is manufactured by projecting the pattern onto a wafer surface by a projection optical system and exposing the wafer through a development process, the illumination system is provided on the light incident side of the optical integrator of the optical integrator. It is characterized by having a light quantity control means for controlling the quantity of light passing through at least one of the plurality of minute lenses.

In particular, (2-1-1) the light quantity adjusting section for controlling the transmitted light quantity of the light quantity controlling means is composed of an ND filter or a light shielding section, (2-1-2) the light quantity controlling means is Is axially movable, and is located at a predetermined distance from a surface optically conjugate with the irradiated surface,
(2-1-3) The light quantity control means has a plurality of types of optical filters or light blocking members having different transmittances and transmission shapes, one of which is selected and inserted into or removed from the optical path. There is.

The ND filter is a Nentral Density filter, which allows a part of light to pass therethrough and absorbs other light, and the light-shielding member absorbs almost all light.

[0013]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

In the figure, 2 is an elliptical mirror. Reference numeral 1 denotes an arc tube as a light source such as a mercury lamp, which has a high-luminance light emitting section 1a for radiating ultraviolet rays, far ultraviolet rays and the like. Light emitting unit 1
“A” is arranged near the first focal point of the elliptic mirror 2. Reference numeral 3 denotes a cold mirror, which is formed of a multilayer film and transmits most infrared light and reflects most ultraviolet light. The elliptical mirror 2 forms a light emitting portion image (light source image) 1b of the light emitting portion 1a near the second focal point 4 via the cold mirror 3.

Reference numeral 5 denotes an optical system, which comprises a condenser lens, a collimator lens, a zoom lens, etc., and controls the light amount control means 1 for the light emitting portion image 1b formed near the second focal point 4.
The incident surface 6a of the optical integrator 6 via
Image. The optical integrator 6 is configured by arranging a plurality of minute lenses 6c having a square cross section in a two-dimensional manner at a predetermined pitch, and forms a secondary light source near the exit surface 6b.

The light quantity control means 17 is movable on the optical axis and is arranged in the vicinity of the light incident surface 6a of the optical integrator 6. The light amount control means 17 controls the amount of light passing through at least one of the plurality of microlenses of the optical integrator 6 by a light amount adjusting unit including an ND filter and a light shielding member. A holder 18 adjusts the illuminance distribution on the illuminated surface 10 by moving the light amount control means 17 on the optical axis based on a signal from an illuminance distribution measuring means (not shown).

Reference numeral 7 denotes an aperture, which determines the shape of the secondary light source. The diaphragm 7 can be switched by a diaphragm exchange mechanism (actuator) 16 so that the various diaphragms 7a and 7b are positioned in the optical path according to the illumination conditions. The diaphragm 7 is composed of, for example, an ordinary circular aperture diaphragm, an annular illumination diaphragm that changes the light intensity distribution on the pupil plane 14 of the projection lens 13 described later, a quadrupole illumination diaphragm, or the like. ing.

In the present embodiment, by using various diaphragms 7, the light flux incident on the condenser lens 8 is variously changed to appropriately control the light intensity distribution on the pupil plane 14 of the projection optical system 13. The condenser lens 8 condenses a plurality of light fluxes emitted from the secondary light source in the vicinity of the emission surface 6b of the optical integrator 6, passes through the diaphragm 7, and is reflected by the mirror 9 to be directed to the masking blade 10 as an irradiation surface. Then, the surface of the masking blade 10 is uniformly illuminated in a superimposed manner. The masking blade 10 is made up of a plurality of movable light shielding plates so that an arbitrary opening shape is formed.

Reference numeral 11 denotes an imaging lens, which transfers the opening shape of the masking blade 10 onto the surface of the reticle 12 as a surface to be illuminated and uniformly illuminates a necessary area on the surface of the reticle 12. Reference numeral 13 denotes a projection optical system (projection lens), which projects the circuit pattern on the surface of the reticle 12 onto the surface of a wafer (substrate) 15 mounted on a wafer chuck. 14
Is the pupil plane of the projection optical system 13.

In the optical system of this embodiment, the light emitting section 1a
The second focal point 4, the incident surface 6a of the optical integrator 6, the masking blade 10, the reticle 12, and the wafer 15 are in a conjugate relationship. Further, the stop 7 and the pupil plane 14 of the projection optical system 13 have a substantially conjugate relationship.

In the present embodiment, with the above-described structure, the pattern on the surface of the reticle 12 is reduced and projected onto the surface of the wafer 15 for reduction projection exposure. The semiconductor device is manufactured through a predetermined development process.

Incidentally, in the present embodiment, the applicant of the present invention described in Japanese Patent Laid-Open No.
As disclosed in JP-A-47626 and JP-A-5-47640, the pupil plane of the projection optical system 13 is selected and used by selecting apertures having different aperture shapes according to the pattern shape on the reticle 12 surface. 14 are variously changed.

Next, the characteristics of the optical operation of the light quantity control means 17 of this embodiment will be described.

FIG. 2A is a schematic view of an optical filter using an ND filter (or a light shielding member) as a light amount adjusting section of the light amount control means 17 of FIG.
FIG. 1B is a side view of essential parts of the light quantity control means (optical filter) 17 and the optical integrator 6 in FIG. 1.

The optical filter 17 shown in FIG. 2 (A) is composed of a plurality of microlenses 7 constituting the optical integrator 6.
c (69 minute lenses shown by dotted lines in the figure), each of which has a light amount adjusting unit capable of adjusting the amount of transmitted light in a plurality of regions. In FIG. 2A, a ring-shaped ND filter 31 that reduces the amount of incident light is included corresponding to one microlens 6d at the center of the optical integrator 1.
The two light quantity adjusting units 21 are shown.

In the ND filter and the light shielding member of this embodiment, a desired transmittance is generally obtained by vapor-depositing a metal film such as Cr or a dielectric multilayer film on the surface of a glass substrate or mixing a dye into the substrate itself. Is configured as follows. Note that other optical members may be used as long as they have the same optical properties as the ND filter.

In FIG. 2 (B), 6c is one microlens of the plurality of microlenses forming the optical integrator 6. The rear focal point of the light incident side lens surface 6c1 of the minute lens 6c is the light emitting side lens surface 6c2.
In the position. The front focal point of the light exit side lens surface 6c2 of the minute lens 6c is located at the light entrance side lens surface 6c1. Therefore, the light beam condensed by the optical system 5 on the lens surface 6c1 of the minute lens 6c is emitted from the lens surface 6c2 as a parallel light beam. The parallel light flux emitted from the lens surface 6c2 is condensed by the condenser lens 8 through the diaphragm 7a, reflected by the mirror 9 and condensed on the masking blade 10. In this way, the light incident surface 6a of the optical integrator 6 and the masking blade 10 have a conjugate relationship.

In the present embodiment, the illuminance distribution formed on the illuminated surface 10 is ideally a superposition of the illuminance distributions on the incident surfaces of the respective microlenses 6c, and may be an optical axis symmetrical system. Therefore, uneven illumination does not occur. However, in reality, illuminance unevenness occurs on the illuminated surface 10 due to flare, decentering of the lens system, coating characteristics of the lens, and the like. FIG. 3 shows an example of uneven illuminance on the wafer surface 15.

Next, a method of correcting the illuminance unevenness will be described by taking as an example the case where the illuminance unevenness as shown in FIG. 3A occurs in this embodiment.

In FIG. 3A, the illuminance unevenness at the intermediate image height is 0.5%, and the number of minute lenses 6c is 69 as shown in FIG. 2A. At this time, in order to correct the illuminance unevenness, the light amount adjusting unit 21 is provided with the ND filter 31 having a ring shape that reduces the transmitted light amount to 65%. The intensity of the light flux transmitted through the ND filter 31 in the zone decreases, and ideally the illuminance is (1-65 / 100) /69×100=0.5 (%) on the plane conjugate with the zone. A decline occurs.

Here, the optical filter 17 is arranged at a position of a predetermined distance D from the incident surface 6a of the optical integrator 6, and ND increases as the distance D increases.
The boundary between the illuminance-decreased portion and the non-illuminated portion due to the filter 17 becomes unclear, and the illuminance is reduced not in a rectangular shape on the image plane (wafer 15) but in a gentle shape (hatched portion in FIG. 3B). In this embodiment, the optical filter 17 is movable in the optical axis direction, and the distance D is adjusted to make the illuminance distribution uniform over the entire image plane. In this embodiment, the amount of light of the small lens on the optical axis (center) is adjusted, so that there is almost no deviation in telecentricity.

As described above, in this embodiment, in at least one microlens of the microlens group forming the optical integrator, the light amount of a part of the incident surface 6c1 conjugate with the illuminated surface is adjusted. Now, it is assumed that the number of light quantity adjusting units is n, the number of minute lenses is N, the transmittance is T, and the illuminance on the irradiation surface is W. At this time, on the irradiated surface, the N
In a region that substantially corresponds to the shape of the D filter, a minute amount of illuminance W * n * (1-T) / N is reduced.

In this embodiment, an ND filter (or a light-shielding member) having a substantially similar shape corresponding to a region having a high illuminance on the surface to be illuminated is provided, and the transmittance is adjusted to make the illuminance on the surface to be illuminated uniform. Has been fixed. As a method of adjusting the illuminance correction amount, it is possible to increase the distance D between the ND filter (or the light blocking member) and the incident surface of the optical integrator to reduce the rate of decrease in illuminance on the irradiated surface. ND filter (or light blocking member)
By adjusting the distance between the optical integrator and the incident surface of the optical integrator, the illuminance adjustment range is adjusted by blurring the shape of the light amount adjustment portion.

Generally, the effective light source distribution (light intensity distribution) on the pupil plane of the projection optical system (projection lens) greatly affects the image performance (resolution) of the projected pattern image. Therefore, in this embodiment, an optimal illumination method is used for each process as an exposure apparatus for manufacturing a semiconductor device. For example, the applicant of the present application
-204121, JP-A-7-29816,
An illumination system is proposed in which the intensity distribution on the pupil plane of the projection optical system proposed in Japanese Patent Laid-Open No. 7-66121 is changed.

In this embodiment, for example, so-called quadrupole illumination is used, which is proposed in these publications, in which the intensity distribution of four regions on the circumference is adjusted around the optical axis. In general, when trying to control various light intensity distributions on the pupil plane of the projection optical system by using diaphragms having different aperture shapes, the illuminance distribution on the reticle plane may become nonuniform. Therefore, in the present embodiment, by using diaphragms having different aperture shapes, for example, the illuminance distribution on the illuminated surface generated when various effective light source distributions on the pupil plane of the projection optical system are changed by, for example, quadrupole illumination. The nonuniformity is improved by using the light quantity control means 20 as shown in FIG. 4 which reduces the light transmission quantity in the four regions 20a to 20d.

In FIG. 4, the light transmission amounts of the light amount adjusting portions 20a to 20d corresponding to the four minute lenses are adjusted. In the case of quadrupole illumination, the light amounts of the four effective light sources are set to be the same in order to substantially eliminate the shift of the telecentricity. In addition, the number of optical integrators used for superimposed illumination is smaller than that for normal illumination.
Therefore, the contribution of one microlens on the illuminated surface increases, and the transmittance of the ND filter used increases. In this embodiment, the illumination conditions (quadrupole illumination, etc.)
The optical filter can be selected by the exchange mechanism 16 so that the most uniform illuminance distribution on the surface to be illuminated can be obtained when is changed.

FIG. 5 is a plan view of the essential parts of various light quantity control means applicable in this embodiment according to the correction shape of the illuminance distribution.

In FIG. 5A, a circular light amount adjusting portion is formed at the center of the optical filter. This shape is suitable for correcting a central hot spot on the irradiated surface. FIG.
In (B), not only the central microlens but also the circular light amount adjusting units are arranged not only in the microlenses at the center but also in the microlenses located at the four apexes of the square that are rotationally symmetric with respect to the other optical axis (center).
However, although the light transmittances of the five light amount adjusting portions are equal to each other here, the light transmittances of the central and other four light amount adjusting portions may be different from each other. FIG. 5C shows the optical filter 1.
A light amount adjusting portion for the ring zone is formed at the center of 7, and it is effective for correction when the illuminance of the ring zone on the illuminated surface is high. FIG.
In (D), a light amount adjusting portion having a shape like a square hole is formed in the center of the optical filter, and it is effective for correction when the illuminance of the peripheral portion on the irradiated surface is high. As described above, in the present embodiment, the shape of the light quantity adjusting unit is optimized in accordance with the shape of the uneven illuminance, and uniform illuminance on the image surface is easily obtained.

FIG. 6 shows a flow of manufacturing a semiconductor device (semiconductor chip such as IC or LSI, liquid crystal panel, CCD or the like).

In step 1 (circuit design), a semiconductor device circuit is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design.

On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4
The (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer.

The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip by using the wafer manufactured in step 4, an assembly process (dicing, bonding), a packaging process (chip encapsulation). Etc. are included.

In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 7 shows the detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface.

In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer.

In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist are scraped off. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to easily manufacture a highly integrated semiconductor device, which has been difficult to manufacture conventionally.

[0048]

As described above, according to the present invention, when the illumination system including the optical integrator is used as the secondary light source forming unit to illuminate the surface to be illuminated, the light amount control unit appropriately set is used as the illumination system. And a projection exposure apparatus capable of easily illuminating a surface to be illuminated with various deviations in the degree of telecentricity, and easily transferring various patterns on a reticle surface onto a wafer surface with high resolution. A method of manufacturing a semiconductor device using can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a positional relationship between the light amount control means and the optical integrator according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a change characteristic of the illuminance distribution on the illuminated surface according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing the shape of an ND filter effective for quadrupole illumination.

FIG. 5 is an explanatory diagram showing various examples of ND filters.

FIG. 6 is a flowchart of a method for manufacturing a semiconductor device according to the present invention.

FIG. 7 is a flowchart of a method for manufacturing a semiconductor device of the present invention.

[Explanation of symbols]

 1 Mercury Lamp (Light Source) 2 Elliptical Mirror 5 Zoom Lens (Optical System) 6 Optical Integrator 6c Microlens 7 Aperture 8, 11 Lens 10 Masking Blade 12 Reticle 13 Projection Optical System 15 Wafer 17 Light Quantity Control Unit 18 ND Filter Adjustment Mechanism 21 Light Quantity Adjustment unit 31 ND filter

Claims (8)

[Claims] 1. A pattern on a surface to be illuminated is illuminated by an illumination system having an optical integrator composed of a plurality of minute lenses forming a secondary light source, and a light beam from a light source is projected onto the substrate surface by a projection optical system. When projecting and exposing, the illumination system has a light amount control means for controlling the light amount passing through at least one microlens of the plurality of microlenses of the optical integrator on the light incident side of the optical integrator at the center of the optical integrator. A projection exposure apparatus comprising a microlens or at least one of four microlenses which are rotationally symmetrical with respect to the center and are located at the apexes of a square. 2. The projection exposure apparatus according to claim 1, wherein the light amount adjusting section for controlling the transmitted light amount of the light amount control means is composed of an ND filter or a light shielding member. 3. The projection exposure according to claim 1, wherein the light amount control means is movable on the optical axis and is located at a predetermined distance from a surface optically conjugate with the irradiated surface. apparatus. 4. The light amount control means has a plurality of types of optical filters or light blocking members having different transmittances and transmission shapes, one of which is selected and inserted into or removed from the optical path. 1. Projection exposure apparatus. 5. A pattern on a reticle surface is illuminated by an illumination system having an optical integrator composed of a plurality of minute lenses forming a secondary light source, the light flux from the light source,
After the pattern is projected onto a wafer surface by a projection optical system and exposed, when the wafer is subjected to a developing process to manufacture a semiconductor device, the illumination system includes a plurality of the optical integrators on the light incident side of the optical integrator. 5. A method of manufacturing a semiconductor device, comprising: a light amount control means for controlling the amount of light passing through at least one of the micro lenses. 6. The method of manufacturing a semiconductor device according to claim 5, wherein the light amount adjusting unit for controlling the amount of transmitted light of the light amount control means is composed of an ND filter or a light shielding unit. 7. The semiconductor device according to claim 5, wherein the light amount control means is movable on the optical axis and is located at a predetermined distance from a surface optically conjugate with the irradiated surface. Manufacturing method. 8. The light amount control means has a plurality of types of optical filters or light blocking members having different transmittances and transmission shapes, one of which is selected and inserted into or removed from the optical path. 5. The method for manufacturing a semiconductor device according to 5.