CN103048894B - Photoetching machine projection lens wave aberration on-line measuring device and method - Google Patents

Abstract

The invention discloses a photoetching machine projection lens wave aberration on-line measuring device and method, wherein the device comprises a light source, a projection lens, a detector, a working table and a mask plate, wherein the mask plate comprises a multi-illumination mode template and a test mark; the test mark is imaged by laser by means of the projection lens; the detector is provided with a reference mark and a photoelectric sensor below the reference mark; the laser enabling the test mark to be imaged is radiated on the photoelectric sensor after passing through the reference mark; the working table supports the detector, can move horizontally or vertically, can determine the position of the test mark image according to the intensity of electric signals output by the photoelectric sensor, and can obtain the wave aberration of the projection lens on line according to a matrix representing the projection lens aberration and the position displacement quantity relationship. According to the invention, the position displacement quantity can be measured under the multi-illumination mode through primary illumination and primary measurement, and the projection lens wave aberration detection speed is improved obviously.

Description

A kind of wave aberration of photo-etching machine projection objective on-line measurement apparatus and method

Technical field

The invention belongs to optical record technology field, be specifically related to a kind of on-line measurement apparatus and method of wave aberration of photo-etching machine projection objective, particularly adopt the apparatus and method of aerial image sensor on-line measurement wave aberration.

Background technology

Along with litho machine critical size constantly reduces, also more and more less to the requirement of projection objective wave aberration, for advanced litho machine, the wave aberration of General Requirements projection objective is not more than several nanometers.In the actual use of projection objective, due to the impact of the caused projection objective thermal effect of Ear Mucosa Treated by He Ne Laser Irradiation and surrounding environment, it is large that the wave aberration of projection objective can become gradually, therefore a kind of projection objective wave aberration on-line measurement device need to be installed in litho machine inside, to measure in real time projection objective wave aberration, if desired by regulating projection objective movable lens that projection objective wave aberration is adjusted to OK range, to ensure the exposure quality of lines.

The wave aberration of projection objective can affect the image quality of mark, so by the parameter of measurement markers picture, also can obtain the wave aberration of projection objective.Prior art 1 (Hans van der laan, Marcel Dierichs, Henk van Greevenbroek, etc. " Aerial image measurement methods for fast aberration set-up and illumination pupil verification ", Proc.SPIE 2001, 4346, 394-407) a kind of measuring method based on transmission image-position sensor (TIS) is proposed, TIS is made up of measurement markers and square hole and light intensity detector, square hole is for the variation of measurement light source intensity, be used for normalization measuring-signal, the impact of fluctuating on measurement result to eliminate the intensity of light source.The light beam irradiates measurement markers of different light illumination modes, because be subject to the impact of projection objective wave aberration, the horizontal level of imaging mark and upright position can change, utilize light intensity detector to measure the position offset of marker image, the sensitivity matrix of the position that goes out of recycling software emulation to wave aberration, can obtain the wave aberration of projection objective.Utilize the method to measure wave aberration, simple in structure, be easy to be integrated in litho machine inside, but because need the position offset of measurement markers under multiple lighting condition, the conversion of different lighting conditions and parameter arrange length consuming time, measuring speed is slow.

Prior art 2 (US 6646729) is equally with the multiple light illumination mode test badge that throws light on, but be different from prior art 1, it utilizes FOCAL (FOcus CALibration use alignment system) technology, by detect best focal plane with alignment system, and then measure the vertical offset of marker image, utilize DISTO (Distortion-measuring technique) technology, by distortion measurement technology, measure the horizontal offset of marker image, utilize sensitivity matrix, obtain the wave aberration of projection objective, this utilization the mature technology in litho machine, aim at and distortion measurement technology, obtain the vertical and horizontal offset of marker image, improve measuring accuracy, but the same with prior art 1, because use multiple lighting condition, measuring speed is slow.

Prior art 3 (CN 101320219A) utilizes TIS sensor measurement to go out the space distribution of marker image, obtain the simulation image of mark by software, the difference of computation and measurement picture and simulation image, the relatively difference of the two, utilize certain algorithm, wave aberration used while going fixed software emulation, until it is close with simulation image or consistent to measure picture, now the wave aberration in software is the wave aberration of surveyed projection objective, because the process that the method solves aberration is optimized, do not need so much lighting condition (compared to existing technology 1 and prior art 2 reduce 3-5 doubly), improve the measuring speed of projection objective wave aberration.But this Technology Need gathers all data of marker image, and calculated amount is large, algorithm complexity, is difficult for improving measuring accuracy.

Summary of the invention

(1) technical matters that will solve

Measure wave aberration speed for prior art slow, the overlong time needing, the present invention proposes a kind of wave aberration measurement mechanism, significantly improves wave aberration measuring speed.

(2) technical scheme

For solving the problems of the technologies described above, the present invention proposes a kind of wave aberration of photo-etching machine projection objective on-line measurement device, comprise light source, projection objective, detector and worktable, described light source is for shoot laser, described device also comprises mask plate, on it, there is test badge, described laser by this test badge via described projection objective imaging; Described detector has a surface and the photoelectric sensor below this surface, on described surface, is provided with reference marker; The described laser that test badge is carried out to imaging is radiated on described photoelectric sensor after this reference marker; Described worktable is used for carrying described detector, this worktable can move up at level, Vertical Square, when it is in the time that horizontal or vertical direction moves, the position of test badge picture can be judged according to the intensity of the electric signal of described photoelectric sensor output, the wave aberration of described projection objective can be obtained online according to the matrix that represents projection objective aberration and position offset relation.

The present invention also proposes a kind of wave aberration of photo-etching machine projection objective On-line Measuring Method, comprises the steps: to make the laser of light source generation through a mask plate, and described mask plate has test badge; Described laser by this test badge via projection objective after imaging; The described laser that test badge is carried out to imaging irradiates on a photoelectric sensor after a reference marker; Described photoelectric sensor is moved in horizontal or vertical direction, judge the position of test badge picture according to the intensity of the electric signal of described photoelectric sensor output, obtain online the wave aberration of described projection objective according to the matrix that represents projection objective aberration and position offset relation.

(3) beneficial effect

The present invention is by integrated multiple lighting condition on mask plate, the integrated multiunit detector of detector, only need to can realize through once illumination and one-shot measurement the measurement of many light illumination modes upper/lower positions side-play amount, improve significantly the speed of projection objective wave aberration detection.

Brief description of the drawings

Fig. 1 is the structural representation of wave aberration of photo-etching machine projection objective on-line measurement device of the present invention;

Fig. 2 shows very, the poor impact on measurement markers position of idol;

Fig. 3 is the schematic diagram of a specific embodiment of mask plate of the present invention;

Fig. 4 shows the pattern of an embodiment of many light illumination modes template of the present invention;

Fig. 5 shows the schematic diagram of an embodiment of measurement markers of the present invention and reference marker;

Fig. 6 has shown the structural representation of an embodiment of multielement bar of the present invention;

Fig. 7 shows the pattern of another embodiment of many light illumination modes template of the present invention;

Fig. 8 shows the schematic diagram of another embodiment of the measurement markers of measuring with the intensity of light source of the present invention and reference marker.

Embodiment

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in further detail.

Fig. 1 is the structural representation of wave aberration of photo-etching machine projection objective on-line measurement device of the present invention.As shown in Figure 1, this device comprises light source LA, illuminator IL, mask plate MA, projection objective PO, detector DE and worktable ST.Light source LA shoot laser, the laser that it is launched is irradiated on illuminator IL through mirror M, illuminator IL expands this laser, impinge upon on mask plate MA after shaping, homogenising, on mask plate MA, there is test badge, test badge is radiated on detector DE after projection objective PO imaging, detector DE has a surface, below surface, there is photoelectric sensor, on the surface of detector DE, be provided with reference marker, thus, the Ear Mucosa Treated by He Ne Laser Irradiation of process reference marker, on the photoelectric sensor of detector DE, is converted into electric signal.Worktable ST is used for carrying detector DE, and it has space six-freedom degree, can move up at level, vertical and upper and lower.When worktable ST is in the time that horizontal or vertical direction moves, according to the intensity of electric signal, can judge the position of test badge picture, then obtain projection objective wave aberration according to sensitivity matrix.Described sensitivity matrix is the matrix that represents projection objective aberration and position offset relation.

Projection objective wave aberration can be divided into strange aberration and idol poor.Fig. 2 shows very, the poor impact on measurement markers position of idol, as shown in Figure 2, in the time being irradiated to the light beam process projection objective PO of test badge, corrugated 1 is desirable corrugated, corrugated 2 is strange aberration, and mark can make to be marked as picture occurred level shifted by delta X behind corrugated 2; Corrugated 3 is that idol is poor, and mark can make to be marked as image position during through corrugated 3 axial offset delta Z occurs.

The wave aberration of projection objective mainly contains spherical aberration (Z4, Z9, Z16 etc.), Y-direction coma (Z3, Z8, Z15 etc.), directions X coma (Z2, Z7, Z14 etc.) and astigmatism (Z6, Z13, Z22 etc.) etc.Below with the poor spherical aberration of typical idol (Z4, Z9, Z16 etc.) for example, the solution procedure of wave aberration is described.

Be NA at lighting condition ₁and σ ₁, corresponding 1nm Z9 spherical aberration, the position offset of introducing can be expressed as:

$S_{1,Z9}=\frac{\∂\mathrm{\ΔZ}({\mathrm{NA}}_1,{\mathrm{\σ}}_1)}{\∂Z9}---\left(1\right)$

Wherein footnote " 1 " refers to lighting condition, S _{1, Z9}for the sensitivity of Z9 item.

Affecting mark Z direction side-play amount aberration has: Z4, and Z9, Z16 etc., now the position offset of grating Z direction can be expressed as:

$\mathrm{\ΔZ}({\mathrm{NA}}_1,{\mathrm{\σ}}_1)=\frac{\∂\mathrm{\ΔZ}({\mathrm{NA}}_1,{\mathrm{\σ}}_1)}{\∂Z4}\·Z4+\frac{\∂\mathrm{\ΔZ}({\mathrm{NA}}_1,{\mathrm{\σ}}_1)}{\∂Z9}\·Z9+\frac{\∂\mathrm{\ΔZ}({\mathrm{NA}}_1,{\mathrm{\σ}}_1)}{\∂Z16}\·Z16---\left(1\right)$

When elected majority kind lighting system, side-play amount can be expressed as:

$\left(\begin{array}{c}\mathrm{\ΔZ}({\mathrm{NA}}_1,{\mathrm{\σ}}_1)\\ \mathrm{\ΔZ}({\mathrm{NA}}_2,{\mathrm{\σ}}_2)\\ .\\ .\\ .\end{array}\right)=\left(\begin{array}{ccc}\frac{\∂\mathrm{\ΔZ}({\mathrm{NA}}_1,{\mathrm{\σ}}_1)}{\∂Z4}& \frac{\∂\mathrm{\ΔZ}({\mathrm{NA}}_1,{\mathrm{\σ}}_1)}{\∂Z9}& \frac{\∂\mathrm{\ΔZ}({\mathrm{NA}}_1,{\mathrm{\σ}}_1)}{\∂Z16}\\ \frac{\∂\mathrm{\ΔZ}({\mathrm{NA}}_2,{\mathrm{\σ}}_2)}{\∂Z4}& \frac{\∂\mathrm{\ΔZ}({\mathrm{NA}}_2,{\mathrm{\σ}}_2)}{\∂Z9}& \frac{\∂\mathrm{\ΔZ}({\mathrm{NA}}_2,{\mathrm{\σ}}_2)}{\∂Z16}\\ .& .& .\\ .& .& .\\ .& .& .\end{array}\right)\·\left(\begin{array}{c}Z4\\ Z9\\ Z16\end{array}\right)---\left(2\right)$

Formula (2) can be abbreviated as:

$\stackrel{\‾}{M}=\stackrel{=}{S}\·\stackrel{\‾}{Z}---\left(3\right)$

Wherein for the position offset under multiple lighting condition, can detect by photodetector, for sensitivity matrix, can with software emulation out, for the zernike coefficient that we require, its Chinese style (3) is overdetermined equation, need to use least square method to solve

From above, in order to obtain the wave aberration of projection objective, need to be through repeatedly illumination (generally need left and right ten times, realize by adjusting illuminator IL parameter), survey respectively the side-play amount of test badge under every kind of light illumination mode, therefore measure the chronic of wave aberration.

In order to address this problem, of the present invention prior art is studied, and has proposed a kind of new measuring method and device, this device arranges a set of shaping light path and a set of test badge on mask plate MA.Thus, can realize the measurement of many light illumination modes upper/lower positions side-play amount through once illumination and one-shot measurement, improve significantly the measuring speed of wave aberration.

In the time a set of shaping light path and a set of test badge being set on mask plate MA, illuminating bundle impinges upon after mask plate MA, shaping light path on masked plate MA is adjusted into different light illumination modes, then impinges upon respectively on test badge, impinges upon on detector DE after projection objective.Simultaneously, the present invention on the surface of detector DE, arrange and mask plate MA on the reference marker of light illumination mode equal number, be arranged on below described surface with the photoelectric sensor of the equal number one to one of reference marker, each photodetector is accepted respectively corresponding light intensity.In the time that worktable ST moves, light signal on each sensor is separately converted to electric signal, just obtain the deviation post of test badge picture under multiple light illumination mode by once illumination, one-shot measurement like this, substitution sensitivity matrix, can obtain the wave aberration of projection objective.

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in further detail.

Fig. 3 is the schematic diagram of a specific embodiment of mask plate MA of the present invention.As shown in the figure, mask plate MA comprises diffusion sheet 4, many light illumination modes template 5, convergent lens 6 and test badge 7.Wherein, the effect of diffusion sheet 4 is spatially to carry out homogenising from illuminator IL emitting laser light beam, it can use common diffusion sheet, holographic diffusion plate, DOE (diffraction optical element) and microlens array etc., and the light beam of homogenising impinges upon in many light illumination modes template 5.Many light illumination modes template 5 is mask plates with special characteristic pattern, and described characteristic pattern is the characteristic pattern that can produce multiple light illumination mode, as shown in Figure 4.

Fig. 4 shows the pattern of an embodiment of many light illumination modes template of the present invention.Many light illumination modes template 5 of the embodiment that Fig. 4 shows has the characteristic pattern that three row three are listed as, characteristic pattern 51,52,53 as shown in FIG..Wherein, black region represents light tight, and white portion represents printing opacity.

Laser, after too much light illumination mode template 5, is radiated on convergent lens 6, and convergent lens 6 is required multiple light illumination mode by beam shaping.Convergent lens 6 can be spherical mirror, aspheric mirror or lens group etc., and the light beam after shaping impinges upon on test badge 7, and light beam impinges upon on the reference marker on detector DE after projection objective PO.

The included photoelectric sensor 8 of detector DE is a kind of light intensity sensors, and as photodiode, thermopair etc., are positioned at below reference marker 7, receives all laser beams from reference marker 7 printing opacities.

Fig. 5 has shown the schematic diagram of an embodiment of reference marker and test badge, because the present invention's reference marker and test badge is in the ordinary course of things set to identical pattern and pattern distribution, therefore only has a figure to represent at this.And the pattern position of reference marker and test badge distributes identical with the position distribution of the characteristic pattern in described many light illumination modes template 5.The black part of the reference marker in Fig. 5 or the pattern of test badge is divided expression transmission region.But, it should be noted that the size of reference marker and test badge is different, the ratio of its size is the enlargement factor of projection objective PO, impinges upon on the photoelectric sensor 8 of detector DE through the light beam of reference marker.

Fig. 6 has shown the structural representation of an embodiment of photoelectric sensor 8 of the present invention.As shown in Figure 6, photoelectric sensor 8 is multielement bars, it comprises multiple sensor unit, as sensor unit 81,82,83 etc., the position distribution of each sensor unit distributes consistent with the pattern in test badge 7, and be separately positioned under reference marker, receive and irradiate from corresponding reference marker the laser getting off.When worktable ST level or while vertically moving, distribute and can judge the side-play amount (Δ X, Δ Y, Δ Z) of test badge corresponding light illumination mode from the electric signal of each sensor unit.So just in once illumination, complete the measurement of all parameters in one-shot measurement, improved significantly the measuring speed of projection objective wave aberration.

The present invention is integrated shaping light path and the test badge that can produce multiple lighting device on mask plate MA, many light illumination modes template 5 has realized the spatial filtering to light, realize the variation of illuminating aperture angle NA and illumination coherence factor σ, wherein characteristic pattern 51, 52, 53 produce be ring illumination, in characteristic pattern 51, white portion is transmission region, the outside diameter of white annular determines illuminating aperture angle NA, the ratio of the area of white annulus area and white cylindrical is coherence factor σ, in the time of white cylindrical and annular region variation, as characteristic pattern 51, 52, 53 etc., corresponding illumination numerical aperture angle and coherence factor are also variable, realized multiple light illumination mode, should be noted that, for example, because each light illumination mode (adopts characteristic pattern 51, 52, 53 etc.) while being radiated on test badge 7, the different field positions that are marked in projection objective are not identical, but because the visual field larger (more than 100 millimeter of true field) of projection objective PO, and all test badges are (as 71, 72, 73 etc.) shared Area comparison is little, generally can not exceed 1mm, as shown in Figure 4, each characteristic pattern 51 of many light illumination modes template, 52, 53 diameter is 0.3mm, 3 × 3 distribute, realize altogether nine kinds of illuminations, whole area size is in 1mm left and right, in so little region, the wave aberration of projection objective is close to consistent, the wave aberration that is to say each test badge place is consistent, but light illumination mode difference, meet the requirement of formula (3), therefore still can the very high-precision wave aberration of measuring the each visual field point of projection objective.

Be noted that in Fig. 4, many light illumination modes template can only produce ring illumination, according to the test request of different wave aberrations, change die plate pattern in Fig. 4, also can produce other light illumination modes.Fig. 7 shows the characteristic pattern of another embodiment of many light illumination modes template of the present invention.As shown in Figure 7, characteristic pattern 91 produces traditional lighting, and characteristic pattern 92 produces two utmost point illuminations, and characteristic pattern 93 produces quadrupole illuminating.

Various lighting systems in the above embodiment of the present invention can be combined as required.

Test badge 7 can use chromium plating amplitude mask, can be also phase shifting mask, as replaced shape phase shifting mask, and Rim Phase Shifting Mask, auxiliary phase shifting mask, chromium-free phase-shift mask, attenuated phase-shifting mask etc.Test badge can be the combination of same test badge in addition, can be also the different test badge combinations of optimizing according to different light illumination modes, for the impact of calibration light source fluctuation, also a test badge can be changed to square hole.

Fig. 8 shows the schematic diagram of another embodiment of the measurement markers of measuring with the intensity of light source of the present invention and reference marker.If the pattern 101 of the test badge in Fig. 8 or reference marker is for the Strength Changes of real-time measurement light source, certainly on reference marker, also there is corresponding square hole, finally use the intensity under all marks of signal intensity normalization on corresponding photoelectric sensor, can remove the impact of light source fluctuation on measuring accuracy, improve the measuring accuracy of projection objective wave aberration.

Above-described specific embodiment; object of the present invention, technical scheme and beneficial effect are further described; be understood that; the foregoing is only specific embodiments of the invention; be not limited to the present invention; within the spirit and principles in the present invention all, any amendment of making, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (8)

1. a wave aberration of photo-etching machine projection objective on-line measurement device, comprise light source (LA), projection objective (PO), detector (DE) and worktable (ST), described light source (LA), for shoot laser, is characterized in that:

Described device also comprises mask plate (MA), has test badge (7) on it, described laser by this test badge (7) via described projection objective (PO) imaging;

Described detector (DE) has a surface and the photoelectric sensor below this surface, on described surface, is provided with reference marker;

The described laser that test badge (7) is carried out to imaging is radiated on described photoelectric sensor after this reference marker;

Described worktable (ST) is for carrying described detector (DE), this worktable can move up at level, Vertical Square, when it is in the time that horizontal or vertical direction moves, the position of test badge picture can be judged according to the intensity of the electric signal of described photoelectric sensor output, the wave aberration of described projection objective (PO) can be obtained online according to the matrix that represents projection objective aberration and position offset relation;

Described mask plate (MA) also comprises many light illumination modes template (5) and convergent lens (6), the laser that incides institute's mask plate (MA) by described many light illumination modes template (5) after by described convergent lens (6) shaping, then be radiated on described test badge (7), described many light illumination modes template (5) is the mask plate with special characteristic pattern, and described characteristic pattern is the characteristic pattern that can produce multiple light illumination mode; The pattern position of described reference marker and test badge distributes identical with the position distribution of the characteristic pattern in described many light illumination modes template (5).

2. wave aberration of photo-etching machine projection objective on-line measurement device as claimed in claim 1, is characterized in that, the characteristic pattern of described many light illumination modes template is three row three column distributions.

3. wave aberration of photo-etching machine projection objective on-line measurement device as claimed in claim 1, is characterized in that, described mask plate (MA) also comprises diffusion sheet (4), and it is for spatially carrying out homogenising to laser beam.

4. the wave aberration of photo-etching machine projection objective on-line measurement device as described in any one in claim 1-3, it is characterized in that, described reference marker and test badge have identical pattern and pattern distributes, and the ratio of its size is the enlargement factor of described projection objective (PO).

5. wave aberration of photo-etching machine projection objective on-line measurement device as claimed in claim 4, it is characterized in that, described photoelectric sensor is multielement bar, it comprises multiple sensor units (81,82,83), the position distribution of described each sensor unit distributes consistent with the pattern in described test badge (7), and be separately positioned under described reference marker, receive and irradiate from corresponding reference marker the laser getting off.

6. wave aberration of photo-etching machine projection objective on-line measurement device as claimed in claim 4, it is characterized in that, the characteristic pattern of described many light illumination modes template (5) comprises the characteristic pattern of the ring illumination pattern that can produce, two utmost point light illumination modes and quadrupole illuminating pattern.

7. wave aberration of photo-etching machine projection objective on-line measurement device as claimed in claim 4, is characterized in that, described test badge or reference marker comprise the pattern (101) for the Strength Changes of real-time measurement light source.

8. a wave aberration of photo-etching machine projection objective On-line Measuring Method, is characterized in that, comprises the steps:

Make the laser of light source (LA) generation through a mask plate (MA), described mask plate (MA) has test badge (7);

Described laser by this test badge (7) via imaging after projection objective (PO);

The described laser that test badge (7) is carried out to imaging irradiates on a photoelectric sensor after a reference marker;

Described photoelectric sensor is moved in horizontal or vertical direction, judge the position of test badge picture according to the intensity of the electric signal of described photoelectric sensor output, obtain online the wave aberration of described projection objective (PO) according to the matrix that represents projection objective aberration and position offset relation;

Described mask plate (MA) also comprises many light illumination modes template (5) and convergent lens (6), the laser that incides institute's mask plate (MA) by described many light illumination modes template (5) after by described convergent lens (6) shaping, then be radiated on described test badge (7), described many light illumination modes template (5) is the mask plate with special characteristic pattern, and described characteristic pattern is the characteristic pattern that can produce multiple light illumination mode; The pattern position of described reference marker and test badge distributes identical with the position distribution of the characteristic pattern in described many light illumination modes template (5).