Background technology
Adopt the optical system of high-pressure sodium lamp illumination in the existing photoetching method, mainly to three-way exposure of g (436nm) h (405nm) i (365nm), obtain certain photoresist figure on the silicon chip of photoresist scribbling, make by steps such as etchings again to obtain same photoresist figure on the silicon chip.
According to different exposure requirements, need different exposure visual field, numerical aperture or coherence factor on the silicon chip face sometimes.And, need and can on the illuminated area of illuminator, produce the most uniform intensity distributions, can set the various different light illumination modes of illuminator, this helps to improve the quality of exposure and obtains better live width.Normally used is traditional lighting pattern and the ring illumination pattern with various different coherence factors.
Disclose a kind of lighting device that can change coherence factor and light illumination mode that uses mercury lamp in the U.S. Pat 5379090, as shown in Figure 1, used the method for blocking to obtain different ring illumination patterns.According to the analysis of this patent, annular has 25% energy loss in this way than being set to 0.5, if with the coherence factor under the way of the blocking change traditional lighting pattern, changes to 0.3 from 0.7, and energy loss will reach 80%.
U.S. Pat 5245384 discloses the illuminator of the noenergy loss of another kind of use mercury lamp, changes coherence factor thereby utilize zoom lens to change the secondary source size, as shown in Figure 2.This structure can be good at avoiding energy loss, obtain the variation of coherence factor, but this structure can't change light illumination mode.
Summary of the invention
Purpose of the present invention provides a kind of photo-etching illuminating apparatus that can produce even illuminated field, can use still less element simply to change light illumination mode and illumination coherence factor, and not need to change element.
The present invention discloses a kind of photo-etching illuminating apparatus that uses the mercury lamp light source, comprising: a mercury lamp light source; One reflector is used for assembling the luminous energy of mercury lamp; One pupil apparatus for shaping is used for producing the pupil of continuous variable and changes light illumination mode; One light balancing device is to obtain better illumination uniformity; One condenser system; One mercury lamp apparatus for adjusting position, by the position of mobile mercury lamp, the coherence factor of the light that change mercury lamp light source sends obtains needed illuminated field.
Wherein, the pupil apparatus for shaping comprises the fixed mirror group, axle vertebra mirror, movable mirror group; The movable mirror group comprises at least three group movable lens.
Wherein, the pupil apparatus for shaping comprises the movable mirror group, movable axis vertebra mirror group and fixed mirror group; The movable mirror group comprises at least two group movable lens.
Wherein, axle vertebra mirror group is a recessed axle vertebra mirror and a protruding axle vertebra mirror; Protruding axle vertebra mirror element comprises two optical surfaces: a circular conical surface, and another optical surface has certain curvature; When the design of illumination coherence factor changes, move every group of movable mirror group and protruding axle vertebra mirror.
Wherein, the mercury lamp apparatus for adjusting position makes mercury lamp regulate automatically in X, Y, three directions of Z; The mercury lamp apparatus for adjusting position cooperates with the pupil apparatus for shaping and obtains suitable pupil, changes coherence factor.
Wherein, light illumination mode comprises circular illumination and two kinds of patterns of unconventional ring illumination that tradition is conventional.
Wherein, the radius of helping to effect a compromise of circular illumination pattern changes as required continuously, and the inner and outer ring radius of ring illumination pattern changes as required continuously.
Wherein, condenser system has adopted minimum a slice reflection type optical element, to reach the turnover of light path; Last a slice of condenser system and the distance between the illuminated field are greater than 100mm, so that the arrangement space of other functional parts.
Wherein, light balancing device is the structure of microlens array and quartz pushrod combination, and according to the light ray propagation direction, a slice microlens array places before the quartz pushrod at least.
Wherein, the quartz pushrod xsect is rectangle or square, and length is greater than 250mm.
Lighting device provided by the invention can use still less element simply to change light illumination mode and illumination coherence factor, and not need to change element.
Embodiment
Below, describe in detail according to a preferred embodiment of the invention in conjunction with the accompanying drawings.
As shown in Figure 3, the present invention discloses a kind of photo-etching illuminating apparatus that uses the mercury lamp light source, comprising: a mercurylamp light source 110; A mercury lamp apparatus for adjustingposition 170, by the position of mobile mercury lamp, the coherence factor of the light that change mercurylamp light source 110 sends; Areflector 120 is used for converging the luminous energy of mercury lamp; A pupil apparatus for shaping 130 is realized the conversion of light illumination mode and the variation of illumination coherence factor; Alight balancing device 140 is to obtain better illumination uniformity; Acondenser system 150; And illuminated field 160.Reflector 120 is collected the luminous energy ofmercury lamp 110, makes it enter pupil apparatus for shaping 130.Pupil apparatus for shaping 130 is used for producing the pupil and the conversion light illumination mode of continuous variable, comprise two kinds of traditional conventional circular illumination and unconventional ring illumination patterns, wherein the radius of helping to effect a compromise of circular illumination pattern can change as required continuously, and the inner and outer ring radius of ring illumination pattern also can change as required continuously.Obtain better illumination uniformity throughlight balancing device 140 again.Aftercondenser system 150 entersilluminated field 160.
Fig. 4 is the embodiment of lighting device of the present invention.Wherein Fig. 4 (a) has adopted different light path turnover modes with Fig. 4 (b), goes for the physical dimension requirement of different lithographic equipments.Lighting device comprises 170, onereflectors 120 of 110, one mercury lamp self-checking devices of a mercury lamp light source, pupil apparatus for shaping 130, and 140, onecondenser systems 150 of light balancing device will be focused on theilluminated field 160 from the uniform beam that quartz pushrod comes out.Wherein, among the embodiment of Fig. 4 (a), pupil apparatus for shaping 130 uses axle vertebra mirror to realize the conversion of light illumination mode.Fig. 4 (a) and light balancing device 140 (b) combine by a microlens array and quartz pushrod.180 is shutter among the figure, can occlusion part branch produce dysgenic parasitic light to subsequent optical path.
Fig. 5, Fig. 6 are the embodiment of pupil apparatus for shaping 140.Pupil apparatus for shaping 140 comprises the fixed mirror group, axle vertebra mirror, movable mirror group; The movable mirror group comprises at least three group movable lens.In another preferred embodiment of the present invention, pupil apparatus for shaping 140 comprises the movable mirror group, movable axis vertebra mirror group and fixed mirror group; The movable mirror group comprises at least two group movable lens.Wherein, axle vertebra mirror group is a recessed axle vertebra mirror and a protruding axle vertebra mirror.Protruding axle vertebra mirror element comprises two optical surfaces: a circular conical surface, and another optical surface has certain curvature.When the design of illumination coherence factor changes, move every group of movable mirror group and protruding axle vertebra mirror.Fig. 5 is a preferred embodiment of pupil apparatus for shaping, and wherein 310 and 320 is the movable lens group, moves the variation that can control the illumination coherence factor as requested, the mobile conversion that can realize light illumination mode of axle vertebra mirror 330.From diagram as can be seen, Fig. 5 (a) and Fig. 5 (c) are the traditional lighting pattern, butmovable lens group 310 is different with 320 position, and the light angle of the generation also difference that distributes illustrates can obtain the to throw light on variation of coherence factor of 310 and 320 change in location.Fig. 5 (b) is the ring illumination pattern, and with Fig. 5 (a) contrast, 310 is all identical with 320 position, the mobile conversion that produces light illumination mode of axle vertebra mirror 330.Fig. 6 is another preferred embodiment of pupil apparatus for shaping, and wherein 420 and 430 is the movable lens group, moves the variation that can control the illumination coherence factor as requested, 410 the mobile conversion that can realize light illumination mode.
Fig. 7 is a preferred embodiment of condenser system 150.Condenser system has adopted minimum a slice reflection type optical element, to reach the turnover of light path.Last a slice of condenser system and the distance between the illuminated field are greater than 100mm, so that the arrangement space of other functional parts.In the present embodiment, use 9 optical mirror slips to form, the centre adds a catoptron with the turnover light path, this composition structure can obtain the even illuminated field of the needed suitable dimension size of lithographic equipment so that the light that comes out from even photosystem has good disposition far away and edge sharpness by thissystem.Condenser system 150 can have various implementation method, and taking a single example at this is illustrated.
Fig. 8 is the synoptic diagram of two kinds of lighting systems that illuminator provided by the present invention realized.Wherein, Fig. 8 (a) is traditional circular light illumination mode, and Fig. 8 (b) is the ring illumination pattern, can see, onilluminated field 160, two kinds of light illumination modes have different distribution of light.
Fig. 9 is the synoptic diagram of mercury lamp regulating device.As shown in the figure, mercury lamp can be regulated automatically in X, Y, three directions of Z, wherein the automatic adjusting of Z axle cooperates with the pupil apparatus for shaping, by the adjusting of Z axle, change the Z axial coordinate that focuses on through the reflector beam reflected, cooperate moving of movable mirror group in the pupil apparatus for shaping simultaneously, can change coherence factor, obtain bigger coherence factor variation range, reduce the design difficulty of pupil apparatus for shaping and the quantity of minimizing movable mirror group simultaneously, improve performance and also reduce cost.
The implementation of light-beam forming unit cooperates with mercury lamp regulatingdevice 170, when needs change the coherence factor of lighting device, automatic Z axle by mercury lamp moves, change the Z axial coordinate of mercury lamp light source through the light beam focusing of reflector focusing, the position change that is equivalent to theinlet 180 of light-beam forming unit 130, be equal to the movable lens group that has increased light-beam forming unit 130, cooperate moving of other movable lens groups, reach the purpose that changes coherence factor.Use mercury lamp regulatingdevice 170, can when not reducing performance, reduce by 130 movable lens group quantity, thereby simplify the structure, reduced cost.
Under the irremovable situation of mercury lamp, use the structure coherence factor variation range of 3 groups, 4 groups, 5 groups, 6 groups movable lens as shown in the table respectively:
And if mercury lamp is regulated automatically, can be reduced to 3 groups of movable lens, can reach [0.38,0.85] under the traditional mode, the coherence factor scope of circular pattern minimum delta σ 0.37 approaches to use 6 groups of movable lens.
Figure 10 is the structural drawing of light balancing device 140.Light balancing device is the structure of microlens array and quartz pushrod combination, and according to the light ray propagation direction, a slice microlens array places before the quartz pushrod at least.Wherein, the quartz pushrod xsect is rectangle or square, and length is greater than 250mm.Among Figure 10 (a), 810 is microlens array, 820 is reflecting surface, beam reflection is gone in thequartz pushrod 830,microlens array 810 can be placed as order among Figure 10 (b) withquartz pushrod 830, also can be as the placement that meets at right angles among Figure 10, the turnover of carrying out light path with a reflecting surface is to reduce the volume of entire lighting device.Light balancing device 140 is combined by a microlens array and quartz pushrod, microlens array and quartz pushrod all can be separately as light balancing devices, and after both are combined, for the lighting device that uses mercury lamp as the photoetching light source, the particularly less mercury lamp of electrode, the big etching system of coherence factor variation range, can obtain better illumination uniformity than both independent uses, under same uniformity requirement, use both combinations then can reduce quartz pushrod length, obtain littler system dimension.
For example using the quartz pushrod of length as 500mm, is 0.88 o'clock at coherence factor, and homogeneity can be better than 1%, but coherence factor is 0.33 o'clock, and homogeneity then is 4.5%, because coherence factor hour, reduces at quartz pushrod internal reflection number of times, homogeneity reduces.If use quartz pushrod and the lenticule combination of length as 500mm, coherence factor is 0.33 o'clock, and homogeneity can be better than 1%.
Described in this instructions is several preferred embodiment of the present invention, and above embodiment is only in order to illustrate technical scheme of the present invention but not limitation of the present invention.All those skilled in the art all should be within the scope of the present invention under this invention's idea by the available technical scheme of logical analysis, reasoning, or a limited experiment.