TW512425B - Method for minimizing optical proximity effects - Google Patents

Abstract

Optical proximity effects (OPEs) are a well-known phenomenon in photolithography. OPEs result from the structural interaction between the main feature and neighboring features. It has been determined by the present inventors that such structural interactions not only affect the critical dimension of the mail feature at the image plane, but also the process latitude of the main feature. Moreover, it has been determined that the variation of the critical dimension as well as the process latitude of the main feature is a direct consequence of light field interference between the main feature and the neighboring features. Depending on the phase of the field produced by the neighboring features, the main feature critical dimension and process latitude can be improved by constructive light field interference, or degraded by destructive light field interference. The phase of the field produced by the neighboring features is dependent on the pitch as well as the illumination angle. For a given illumination, the forbidden pitch region is the location where the field produced by the neighboring features interferes with the field of the main feature destructively. The present invention provides a method for determining and eliminating the forbidden pitch region for any feature size and illumination condition. Moreover, it provides a method for performing illumination design in order to suppress the forbidden pitch phenomena, and for optimal placement of scattering bar assist features.

Description

^ 1 ^ 425 A7 ^ __________ 5. Description of the invention (彳) 1. The present invention is related to lithography, and more particularly to the light proximity correction method used in lithography masks used in the manufacture of semiconductor devices. Lithography devices can be used, for example, in the manufacture of integrated circuits (ICs). In this case, the photomask usually includes a circuit pattern corresponding to individual layers of c, and a radiation projection beam used to map this pattern to various substrates (Shi Xi wafers) covered with a layer of radiation-sensitive material (resistance). Target sections (each containing one or more dies). Usually a single wafer contains the entire network of adjacent target parts, one after the other one at a time. In a lithography device, the entire mask pattern is exposed on each target portion to illuminate the target portion. This device is generally called a wafer stepper. In another device commonly referred to as a step scanning device, the projection beam scans the mask pattern line by line in the existing direction (the scanning direction), and simultaneously scans the substrate in parallel or antiparallel to this direction to illuminate each target. Part; when the magnification factor of the projection system is M (usually < 1), the speed v of scanning the substrate is the factor M times the speed of the scanning mask pattern. For more information on the lithographic apparatus described herein, refer to, for example, US 6,046,792, which is hereby incorporated by reference. Lithography devices can use a variety of projected radiation, many examples of which include ultraviolet (UV) radiation (such as 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm), ultra-UV ("EUV"), X-ray, ion Beam or electron beam. Depending on the type of radiation used and the specific design requirements of the remote device, it may include projection systems with refractive, reflective, or self-curvature optical elements, as well as elements including glare states, grazing incidence mirrors, selective multilayer coatings, magnetic and / or electrostatic field mirrors, etc. For simplicity, this component will be referred to as the "mirror" alone or collectively in this article. -4-This paper size is in accordance with Chinese National Standard (CNS) A4 specification (210 X 297 mm) 512425 A7 B7 5. Description of the invention (2), installed in the process using this lithography technology device, a mask style in Imaging on a substrate at least partially covered by a light-emitting sensing material (resistive agent). Prior to this imaging step, the substrate can be subjected to various procedures such as ignition, resist coating and soft baking. After exposure, the substrate can be subjected to other procedures such as post-exposure baking (PEB), development, hard baking, and imaging characteristic measurement / inspection. This set of procedures serves as the basis for styling individual layers of devices such as integrated circuits (ICs). This patterned layer can then be subjected to various processes such as etching, ion implantation (doping), metallization, oxidation, chemical mechanical polishing, etc. to polish individual layers. If several layers are required, each new layer needs to repeat the entire process or changes in the process. Finally, there will be a set of devices on the substrate (crystal circle). These devices are separated from each other by techniques such as cutting or sawing, and individual devices can be mounted on a carrier and connected to pins. Additional information on this process can be found in "Microchip Fabrication: A Practical Guide to Semiconductor Processing", third edition by Peter van Zant, McGraw Hill Publishing Co., 1997 ISBN 0-07-067250-4.

When semiconductor manufacturing technology is rapidly approaching the lithographic limit, the processing technology to date has typically produced critical dimensions (CDs) of ICs at this exposure wavelength ("again"). The critical dimension of a circuit is defined as the minimum space between two characteristics or the minimum width of a characteristic. For characteristic patterns designed to be smaller than λ, it is found that the optical proximity effect (OPE) is too serious, in fact, is not allowed by the cutting-edge sub-λ process. Light proximity is a well-known feature of optical projection exposure tools. That is, the proximity effect occurs when closely spaced circuit pattern lithography is transferred to a resistive layer on a wafer. The light wave interaction that closely separates the characteristics of the circuit makes the final transfer-like -5- This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 512425 A7 B7 V. Description of the invention (Type 3 characteristics are distorted. That is, diffraction causes adjacent characteristics to interact with each other in a manner that makes the pattern dependent. The size of a given characteristic is related to the position of the characteristic relative to the other characteristics of the mask. One of the main problems caused by this adjacent effect is the characteristic. CDs have undesired changes. For any cutting-edge semiconductor processing, CDs with tightly controlled characteristics (ie, circuit components and interconnects) are usually the highest targets for manufacturing, because this will directly affect the acquisition of, Rate and productivity speed. The change in the circuit characteristics CDs caused by OPE is known to be reduced by some methods. One technique is related to adjusting the exposure characteristics of the exposure tool. That is, the careful selection of the numerical aperture (NAc) of the condenser to the rhodium numerical aperture ( NAo) ratio (this ratio is regarded as a partial coherence ratio) · σ can control the degree of OPE to a considerable degree. In addition to using non-coherent irradiation as described above, it can also be used Pre-correction of the reading mask to compensate for OPE. This type of technology is commonly referred to as optical proximity correction (0pc) technology. For example, US Patent No. 5,242,770 (the 770 patent), incorporated herein by reference, describes the use of OPC's scattering bars (SBs). The 770 patent shows that the SB method is very effective in improving the insulation characteristics, so the characteristics have dense characteristic behavior. This also improves the depth of focus (DOF) of the insulation characteristics, so the processing range is greatly increased. The scattering strip (also (Referred to as a brightness level bar or an auxiliary bar) is a correction characteristic (usually unrecognizable by an exposure tool) for adjusting the intensity gradient of an insulating edge placed next to an insulating characteristic edge of the photomask. Preferably, the intensity gradient and The dense characteristic edge-to-edge intensity gradient matches, so the SB auxiliary insulation characteristic has the same width as the dense characteristic. For large characteristic sizes under traditional irradiation, it is generally considered that the processing range related to the dense structure is better than that related to the insulation structure. Stronger used -6- This paper size applies to China National Standard (CNS) A4 specifications (210X297 mm)

Irradiation architecture, 4 s. When using this irradiation and multipolar irradiation as an improved analytical device, the invention is more obvious. In particular, the first two phenomena of Tailu π became within the scope, and the tight people discovered a phenomenon of forbidden spacing. That is, in the pitch garden, the processing range of the main characteristics, especially the exposure range characteristics, is not fixed: :: edge :: poor. This observation by Wang Yao shows that the adjacent one is printed on the characteristic of Wang, which is the same as the discovery of the present invention: two. In fact, the inventor believes that the forbidden space phenomenon has become a useful factor. Therefore, the suppression of the forbidden space phenomenon is necessary to further modify the manufacturing tools and techniques available for the device. Therefore, the present invention is related to various methods and techniques for finding and eliminating the forbidden space region that degrades the overall printing performance, so as to improve the processing range and CDs available using the existing lithography tools and techniques. SUMMARY OF THE INVENTION The present invention is related to methods and procedures for finding forbidden-pitch areas that have a bad effect on the critical size of the characteristic and the range of characteristic processing, and eliminating the use of forbidden-pitch areas in the design / manufacturing process. That is, the present invention is related to a method for finding an unnecessary distance between characteristics when a lithographic exposure tool is used to form a integrated circuit (or other device) on a substrate. In an exemplary embodiment, the method includes the following steps: (a) determining the peak interaction pitch region by determining a specific irradiation angle irradiation intensity in a pitch range; and (b) determining the specific peak interaction pitch region in a range of irradiation angles; and Irradiation intensity 'find out the distance between the top interaction spacing areas found in step (a). According to the present invention, the change in the critical size and processing range of the main characteristics is directly applicable to the paper size. National yarn (CNS) 4 grid (21G X 297 public love) B7 V. Description of the invention (5 is the main characteristic and the neighboring characteristic Caused by interfering light field interference. Depending on the field phase produced by the neighboring characteristic, the critical size and processing range of the main characteristic can be improved due to constructive light field interference or degraded by destructive light field interference. Field phase produced by the adjacent characteristic The display is related to the distance and the irradiation angle. For a given irradiation angle, the forbidden space zone is the field generated by the adjacent characteristic and the main characteristic field destructively interferes with the position. The present invention provides a method to find any characteristic size and irradiation condition. The method of spacing area (ie, position). More importantly, the present invention provides the adverse effects related to the radiation suppression to suppress the forbidden space phenomenon. In addition, the present invention provides the use of = scattering and suppression of the forbidden space phenomenon to make light close Method for minimizing effects and optimizing overall printing performance. As detailed below, the present invention is far superior to the prior art. More importantly, the present invention can find and eliminate the total printing performance Degraded forbidden space, so improve the CDs and processing range available with existing lithography tools and technologies. Those skilled in the art will understand other advantages of the present invention from the following detailed description of the exemplary embodiments of the present invention. The drawings provide a better understanding of the invention and other objects and advantages.

Schema gjjL Figure 1a illustrates an example imaging system. Figures 1b and 1c illustrate the transformation of the image point on the axis of the light exit pupil to the corresponding point in the two-dimensional frequency plane. Figure 2 represents an exemplary mask pattern printed on a wafer. 3a-3d illustrate example results of on-axis and off-axis irradiation. -8- 512425 A7 B7 V. Description of the invention (6 Figures 4a and 4b illustrate the interaction between two side features with different distances and the main characteristics at a specific irradiation angle. Figure 5 represents two-dimensional irradiation. Figure 6 represents vertical and Conjugate architecture required for horizontal characteristic performance balance. Figure 7 illustrates a detailed flowchart of the process of defining / finding the forbidden space zone. Figure 8 is the result of the processing of Figure 7 illustrating the top interaction space zone. Figure 9 illustrates the generation of a given spaced irradiation A detailed flowchart of the processing of the figure. Figures 10a-10c show the irradiation diagrams corresponding to the 480 nm, 560 nm, and 635 nm top interaction pitch regions illustrated in Figure 8. Figure 10d illustrates the irradiation patterns corresponding to the 3 10 ηι pitch. Figure The illuminated design illustrated in Figure 1 improves the exposure range of the 480 nm pitch region, while maintaining strong constructive structural interactions in other pitch regions. Figure 1 2 illustrates the comparison of the logarithmic slope values of ring, quadrupole, and modified quadrupole illumination. Figure 1 3 Shows a side-to-side placement position of the top interaction of the scattering strips near the isolated main line. Figures 14a-d are radiation diagrams generated by the quadrupole irradiation of the scattering strips separated from the main characteristic changes. The spacing phenomenon is directly caused by the light interaction between adjacent characteristics. That is, the related adjacent characteristic field phases of the main characteristic field phase are related to the irradiation angle and separation distance between these characteristics. For a specific irradiation angle, there are adjacent characteristics. The field phase and the main characteristic field phase are 18 °. The phase is different, and there is a range of destructive interference. In this phase, the destructive interference reduces the image contrast of the main characteristic, and -9-This paper standard applies to China National Standard (CNS) A4 specifications (210 X 297 male: t) equipment

k 512425 A7 -------------- B7 V. ^ Explanation (; ~ _) '~-Causes loss of exposure range. These distance ranges that cause destructive interference are called forbidden distance regions, and can be found and eliminated by the method of the present invention. The method according to the present invention is described in detail as follows. The forbidden space area (that is, the top frame interaction space area) is found by using an irradiation pattern. In one embodiment, the corresponding irradiation maps of the unstructured interaction distances are obtained, showing the better irradiation area and the worse irradiation area. Therefore, the use of this irradiation pattern can eliminate unnecessary forbidden space areas. In addition, Tian is more similar to the size of the scattering bar, which can find similar constructive and destructive interference areas, and can also obtain its corresponding irradiation angle. Based on these radiation patterns, the present invention can also determine the optimal scattering bar configuration for a given irradiation condition. Before discussing the present invention in detail, let's take a brief look at the relevant theory of the method of the present invention. According to Fourier optics, the imaging process can be regarded as a double diffraction process under coherent illumination. The mirror of the Fourier transform device converts the geometric data of the object (that is, Wang Guangmask) into the spatial frequency information of the object's frequency domain. The object's spatial frequency information (ie the frequency part and its amplitude) is presented to the exit pupil of the optical imaging system. If the linear size of the geometry of the object is much larger than the irradiation wavelength, and the foot topology of the object is much smaller than the irradiation wavelength, then the object can be regarded as geometric and can be applied to the scalar diffraction theory. The above assumptions are currently considered to be applicable to a reduced-conductance (reducton pronjection) light imaging system with a binary chromium (chromium) mask. In this case, the exit pupil field is related to the Fourier-transformed object transfer function. In practical lithography systems, although a collimated or reduced projection system is used, the following discussion uses a 1 X system to simplify analysis. 1 X-ray imaging system without 4 × 4 5X reduction projection system Complex imaging pupil pair required for light imaging system -1 〇-This paper is suitable for financial use_ 家 鲜 (CNS)

Optical chirping conversion 'is two frequency conversion, field size conversion and polarization tracking. However, it is to be understood that the present invention is equally applicable to other systems, including 4X * 5X reduction and re-radiation system optical imaging systems or any other available system. Figure 1a illustrates an exemplary imaging system 10 that helps to describe the operation of the present invention. As shown, the imaging system i 0 includes a monochromatic light source 12, a condenser 14, a main mask 16 and a projection mirror 18. It is also shown that the imaging process produces an exit pupil 20 and an image plane 22. The irradiation structure in this system is K0hler irradiation, so a single irradiation is achieved. In addition, if an adjustable aperture light flash is placed behind the projection plane of the projection lens 18, the rear focusing plane becomes the exit pupil because there is no light element between the rear focusing plane and the image plane. When the exit pupil is viewed from the image point on the axis, each geometric point of the exit pupil 20 corresponds to a pair of angular coordinates (θ, +), which can be converted into a two-dimensional frequency through the following described in equation (1) Corresponding points on the plane (as shown in Figures 1b and 1C). kx = sin 0c 〇s φ, ky = sin 0s i η φ… ⑴ Now consider the object with the conversion function shown in Figure 2. This object can be regarded as a one-dimensional object, and its conversion function is: + + ⑽Lu :, + α '2 + +, xQ + (b ^ a / c / 2) ac ^ ~ --- (2) where J1; | X〇l <a; 2 a [0; | x01 < a / 2- -(3) a is the main characteristic (central characteristic) wide, c is the side characteristic (s) wide and b is the main characteristic-11-This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 512425

The edge-to-edge partition between the lateral features is huge. The objects illustrated in Figure 2 represent a generalized reticle pattern. S α = 0 is a binary reticle, J = 0.06 is a 6% attenuation phase shift reticle and α = 1.0 is a phase shift reticle. Coherent irradiation on the axis of a quasi-monochromatic light source (sin0 = 〇), the exit pupil field is ... (4) where kx = sin0 is the spatial frequency of the frequency plane on the axis. It should be known that the coherence length of the π light of the quasi-monochromatic light source table is much longer than the difference in optical path length between any pair of light rays under consideration. This estimate applies to light sources used by lithography, especially KrF excimer light sources that must be less than micron wide. Figures 3a-3d illustrate on-axis and off-axis irradiation along the x-axis. As shown in Figures 3 & 3b, the object spectrum is centered when illuminated on the axis. However, as shown in Figs. 3c and 3d, when the object's spectrum is read out relative to the outgoing light when it is irradiated along the X-axis, the exit pupil field becomes: (5) where kXQ = sine. , And Θ. Is the irradiation angle. This phase e has a simple geometric representation, and illustrates the phase difference between the irradiation fields of different object points (as illustrated in Figure 3c). Inserting equation (2) into equation (5), the result is: -12- This paper size applies Chinese National Standard (CNS) A4 specification (210X297 mm) 512425 A7 B7 V. Description of the invention (10 sin [^ y (/ c,-/ cJ] sin [/ Ty (/ c,-^ J] factory (/ ',) πΑ (/' v 一 / c J 一 (I + ") ί one --ά- +-^-乂 π seek (/ (X — 七 丄 · α) t siη [, τ- ·-(/ {, r- / c.rJ] ^ T7 / »(I, -i .μ) / λ ^ Λ- ------- 1 乂 厂-(/ (. R 一 人 'rJ Λ (6) where p = b + a / 2 + c / 2, is the pattern spacing. According to Fourier optics, the electric field of the image plane is : ^ (M) ^ j Ci ^ C / c,) c2 ^ '' iUd kx ⑺ can re-measure the quantities set by equations (6) and (7), and reduce all geometric sizes to λ / ΝΑ, and kx and kxo are normalized to NA. Specifically, these remeasurements can be expressed as: (Jr = a · ΝΑ / λ, hr = h · ΝΑ / λ, Cr = c · · ΝΑ / λ, pr = ρ · ΝΑ / λ '·,' ·, · ΛΜ / 乂, krt: kx! NA 'd_JNA two s ... ⑻ Using these remeasurements, the image plane electric field becomes: ",, -w ·,,, rif s \ n ^ ar (k: -s)] -2 ^; ^. r) such as) 0 ^… (u machine u + e CrlCr (d (9) or, 7 (Λ ·;) π (·-· η, _ '-( ha) L {< sin [/ Tgr (/ crr ~ J)] ^ π a person krx-Θ f ^ dk: (N- rr) e2 ^ fJ ;; {C /.^ £ L ^ lZ ^ lf ( , Bl ^

K Cr (kx- ^ J-(I + ") (, ^ / νί, ν • (and Γκ% 〆: ^ Cr {kr, -S)… (9,) -13 This paper size applies to Chinese national standards ( CNS) A4 specification (210 x 297 mm) 512425 A7 B7 V. The description of the invention where S is related to the angle of illumination. From equation (9,), it is clear that the field characteristic phase item / A5 produced by the side characteristics. This phase item is The decision and elimination of the forbidden area is important.

Pretend to know that equations (9) or (9 ') apply to one-dimensional irradiation. However, as shown below, the two-dimensional irradiation used in lithography can be close to the one-dimensional irradiation of long lines or trench structures.

As detailed above, it has been known that the exposure range of the main characteristic with some pitch regions in a specific irradiation condition becomes small, even smaller than the insulation characteristic. This interval area is regarded as a forbidden interval area and is caused by destructive interference between the main characteristics and the side characteristics under these irradiation conditions. The side characteristic is to improve or degrade the main characteristic processing range, and it is related to the field generated by the side characteristic of the main characteristic Gaussian image point. If the side characteristic field phase and the main characteristic field phase of the main characteristic image position are the same ', constructive interference between these fields can improve the processing range of the main characteristic. The phase difference between the main characteristic field and the main characteristic image is 180. ’Then the subtraction and subtraction between these fields causes the main characteristic processing range to deteriorate. The forbidden space is located at a position where destructive interference occurs under a predetermined irradiation condition. When this happens, the main characteristic processing range is worse than the insulation range. The field sign (depending on the phase) and the size due to the side characteristics are determined by the pitch, the irradiation angle, and the numerical aperture (NA). Equation (9,) can be used to locate the constructive and destructive interaction pitch zone. Figures 4a and 4b show examples of interactions between the main characteristics and the side characteristics of two different pitches at a specific illumination angle. In these examples, the feature size is 130 run, NA = 0.65 and s = 0.4 (for a binary mask) (α = 0). As shown in Figure 4a, when the pitch is about 470 nm, the main characteristic is the highest in the Gaussian image point. -14- This paper size applies the Chinese National Standard (CNS) A4 specification (210X 297 mm) 512425

Low intensity (dotted line) has higher insulation characteristics (solid line), resulting in lower image contrast and smaller exposure range. As shown in Figure 4b, when the pitch is about 680 nm, the minimum intensity (dashed line) of the main characteristic Gaussian image point is lower than the insulation characteristic (solid line), which makes the image pair higher and the exposure range larger. As mentioned above, the above-mentioned forbidden space region is analyzed based on one-dimensional irradiation, that is, (ky = 0). The illumination structure used by lithography is actually two-dimensional. However, for near-one-dimensional structures such as extremely long lines or trenches, the two-dimensional irradiation problem can be reduced to a one-dimensional problem. The above is described using FIG. 5. Referring to FIG. 5, it is assumed that the structure is infinitely long in the y direction, and the Fourier transform spectrum of the structure of the exit pupil is 0 in the ky direction. In this case, two-dimensional irradiation (NA, kx, ky) is equal to one-dimensional irradiation (NAefifective, Seffective). The relationship between the two-dimensional irradiation and its corresponding one-dimensional irradiation can be obtained: NAc (Trrti \ r = \ l / V // 2 ~ β1… (10) a

SrfTrrfivc = '~ r --------, β < ΝΛ V / V / Π2 where NA of equation (10) is the numerical aperture set by the lithographic projection device used. A more detailed analysis of the forbidden space phenomenon and light irradiation design used to suppress the forbidden space area needs to consider the performance balance between vertical and horizontal characteristics (ie, y and X direction characteristics). In order to achieve this performance balance, as shown in FIG. 6, (kx > 〇, the irradiation source point (α, / 3) in the irradiation space needs to have a corresponding conjugate irradiation source point (kx < 0, ky > 0) in the irradiation space ( -/ 5, α). That is, the irradiation points in the first quadrant and the second.-15- The paper size is suitable for financial standards (CNS) A4 specifications 297 male f 512425 A7 B7 V. Description of the invention (the corresponding irradiation points in the 13 quadrant are 90 degree rotation symmetry. Similarly, in the simplified one-dimensional irradiation space, any irradiation source point (NAeifeaive, Seffeetive) needs a conjugate irradiation point: (, / 八 Ί _ ^ A'cffcctivc Srjfcrfivc > λ / Μ Λ ~ l ^ AcJJcctivc 丨 ~ \ J ΜΛbi / Ccffccdvc Selective) * With this conjugate illumination architecture, the forbidden space area can be found and eliminated. The flowchart in Figure 7 details the process of defining / finding the forbidden space area. The first part of this process Determines the predetermined (α, 0) interaction interval zone. Refer to Figure 7 using equation 9 or 9 f, which is explained above as representing a calculation engine related to one-dimensional irradiation. That is, for a given irradiation point (ie α , Cold is fixed), use equation 9 or 9 to calculate the photos of a given distance I (α, / 3, pitch) Intensity (step 骡 7 0). In addition, use + 9 or 9 · Calculate the irradiation intensity (step 2 7 2) corresponding to 90 degrees of rotation symmetry at the same distance I (-/ 3, a, pitch). Add the two irradiation intensities (step 7 4) to obtain 1_ 0, Θ, pitch), and then calculate the log slope of 1_ (step 7 6). Then repeat for each desired interval I (α, cold, pitch) This process (steps 78, 80). Fig. 8 illustrates the result of the process of Fig. 7 and shows the area with the top interaction space. Referring to Fig. 8, the top space interaction location is found from the area with a considerable amount of circle. The top space interaction position can be found using the following equation: d (log_slope of ita) / d (pitch) s. In particular, the position substantially adjacent to the position satisfying the above equation is the top space interaction position. That is to find the vicinity of the specific position indicated by the above conditions of the top-pitch interaction position, which is the actual forbidden pitch range. The actual range is related to the exposure device wavelength and NA. Experimental research has found that the specific position appendix -16-this paper scale applies China National Standard (CNS) A4 (210 X 297 mm)

Hold

512425 A7 B7 V. Description of the invention (14 near the 'spacing area' is about + Λ0.12 wavelength / NA. For example, when the exposure device uses a 248 nm source and NA = 0.65, the top interaction spacing area is about + / _ 45 nm. Another It should be known that the position of the top interaction space is not static when the position of the top interaction space is very stable. The position of the top interaction space may be slightly shifted when the irradiation angle is moved.

Install back to Fig. 8. Note that the example in Fig. 8 uses a set of scanners with sececdve = 0.65 and NA = 0.65. As shown, there are 4 different top-interaction pitch regions in the middle pitch region (300 nm to 700 nm), located at about 370 nm, 480 nm, 560 run, and 630 nm. Note also that Fig. 8 does not show that the top interaction space area is destructive or constructive, but only shows whether this area exists. In addition, the #top interaction gap area did not change with the irradiation angle. This area is not sensitive to the angle of illumination. Once the top interaction gap area is found, the next part of the process produces an irradiation pattern of the desired spacing (ie, the top interaction gap area). In short, the interaction distance between the tops of the region ’is the main characteristic image logarithmic slope at the edge of the mask as a function of the illumination angle.

Count. The flowchart of FIG. 9 details the process of generating a predetermined top-interaction space irradiation pattern. Referring to FIG. 9, using Equation 9 or 9 ′ again to calculate the irradiation intensity of the fixed pitch and the first irradiation angle (α, / 3) (step 90), and calculate the corresponding 90 degree rotation symmetry point irradiation intensity at the same pitch. (Step 9 2). Then add the two radiation intensities (step 骡 9 4) to obtain Itotal (α, cold, pitch), and then calculate the logarithmic slope of I- (step 骡 9 6). The process is then repeated for multiple illumination angles so that the illumination pattern covers at least one quadrant (i.e., 0 stove, 0 SkySl) (steps 98, 100). Figs. 10a-10c respectively show the irradiation patterns corresponding to the 480 nm '560 nrn and 635 nm top interaction pitch regions described in Fig. 8. -17- This paper size applies the Chinese National Standard (CNS) A4 specification (21 × 297 mm) B7 V. Description of the invention (15 Figure 10d description and irradiation chart corresponding to the minimum distance of 3 10 nm. Referring again to Figures 10a-10d, The irradiation angle corresponding to the higher logarithmic slope value is the irradiation angle that provides the best performance for a given interval. That is, the higher the logarithmic slope value, the better the performance. For example, referring to FIG. 10a, this interval (that is, 48nm) is the best. A good irradiation angle is about 0. The logarithmic slope value of any irradiation angle corresponding to the values of keo.2 and ky> 0.2 is low, so it is not desirable. As shown in Figure 10a, the highest logarithmic slope value is at kxl ky Occurs at approximately 0. Referring to Fig. 10b, the optimum irradiation angle at a pitch of 560 nm is approximately the angle corresponding to kx = 0.51ky = 0, * kx == 0 and ky = 0.5. Referring to Fig. 10c, the 635 The optimal irradiation angle of the nm pitch is about the angle corresponding to kx-0 · 3 and ky-0.3. Finally, referring to Fig. 10d, the optimal irradiation angle of the 3 10nm pitch is and kx = 0 · 5 and ky = The angle corresponding to 0 · 5. Therefore, it can be clear from the irradiation map that the interaction distance between the top or bottom zone is related to the irradiation used. Then review these irradiation maps. The irradiation pattern at a distance of 48nm is complementary to the irradiation patterns of 635nm and 310nm. That is, at a pitch of 480nm, the desired irradiation angle corresponding to kx & ky is approximately equal to 0, and the unwanted regions corresponding to ^ and ^ It is approximately equal to 0.5. On the contrary, at the distances of 635 nm and 3 10 nm, the desired irradiation angle corresponding to kx & ky is approximately 0.5, and the unwanted area corresponding to dagger and a is approximately 0. Unless this layer has no structure at 480 Near the nm interval, otherwise this essential complementary characteristic prevents the use of lithographic quadrupole irradiation at 130 nm mode. The above analysis of the illumination angle allows the designer to choose the illumination angle to be used to optimize printing performance and more importantly to avoid causing The top interaction gap area of destructive interference. The minimum 1_log slope of acceptable performance has been found, partly related to the resist used. For example, different resists have different contrasts, which requires different -18. This paper size applies China National Standard (CNS) A4 specification (210 X 297 mm) 512425 A7 ___ _B7 V. Description of the invention (16) &1; 1 The minimum value of the logarithmic slope corresponds to the best performance zone. But usually the logarithmic slope value is approximately equal to one Greater than acceptable handling The value of 5 results. For the optimization of printing performance, refer to the example irradiation diagrams in Figures 10a and 10d. Compared with quadrupole irradiation, circular irradiation (such as ^ 111 = 〇55 and 1〇ut = 〇85) The image contrast of other spaced areas can be downgraded and the image contrast near the 48nm spaced area can be improved. This method uses the average of the destructive and constructive interactions in the irradiation space to reduce the structural interaction of different spaced areas. For example, the illumination design illustrated in Figure 11 improves the exposure range of the 480 nm pitch region while maintaining strong constructive structural interactions in other pitch regions. That is, the irradiation design illustrated in the figure provides some irradiation at the irradiation center, because the better irradiation of the 48 nm interval region is near the center (kx = 〇, ky == 〇). However, when the central irradiation is increased, it is necessary to consider the performance balance, because the central irradiation will definitely degrade the image contrast ratio of the minimum spacing area of 3 nm. Figure 丨 2 shows the comparison of the logarithmic slopes of ring, quadrupole, and modified quadrupole irradiation (σ-center = 0.15 and \ center = 0.2) using the solid-c simulation software. This characteristic is the 13 nm line of the 6% attenuation phase shift mask. As shown in the far simulation results, the improved quadrupole of Center 2 has better overall processing, and can also fully take advantage of the auxiliary characteristics. The QUASAR in the figure refers to the use of diffractive light elements (DOE) to generate quadrupole radiation, which will redistribute the incoming radiant flux instead of blocking / transmitting it. In particular, 30 degrees (^ 11 8 3 8 11 is considered as a quadrupole ring segment and each quadripole pattern is centered at 30 degrees.) The above-mentioned illumination pattern can also be used to assist the configuration of the scattering strips to reduce the proximity effect. This scattering strip is used in the previously mentioned US No. 5,242,770. As detailed in patent 770, it is known to increase -19- near the rare (such as insulation) characteristics.

V. Description of the invention (17 The auxiliary characteristic is to achieve the best and desired effect of micro-graphics dense printing. The auxiliary characteristic is required. However, the placement is similar to 'possible to place scattering near the main characteristic. The invention disposes the scattering distance Γ 1 distance zone. Therefore, the distance Γ can also be used to ensure that the scattering bar does not fall within the range of the radiation angle. The implementation of the technology involving the scattering bar is large, and the largest scattering bar is used in the agent contrast capability. Two :: Including other factors into consideration, such as the scattering strip 0 inch = difference caused by the mask manufacturing process. Currently, the size of the scattering strip is usually __8Qnm. The configuration of the scattering strip is based on the experimental development configuration rules, such as Mask ·, The special design of the main mask of the uNESWEEPER ™ main body. The principle of placing the scattering bar is similar to the principle of the forbidden space phenomenon. That is, the first step is to find the position of the top interaction between the scattering bar and the main characteristic. The processing of the action position is essentially the same as the above-mentioned processing for finding the top interaction spacing area. However, in addition to finding the small logarithmic slope area necessary to find the forbidden spacing area, it also finds the large logarithmic slope showing the main characteristic. Figure 13 shows the position of the top-to-side interactions of the scattering bars near an insulated main line. The top-to-edge positions are approximately 235 nm, 375 nm, 510 nm, 655 nm, etc. Once identified, The top interaction position, the next step is to choose the irradiation pattern and the process has selected the similar irradiation conditions. It should be noted that the closer the scattering strip and the main insulation characteristics are not necessarily better, because each configuration position has its own better irradiation Figures 14a-d are photos of the quadrupole irradiation of the scattering strip separated from the main characteristic changes. -20- This paper size applies the Chinese National Standard (CNS) Λ4 specification (210X297 mm) 512425 A7 _______B7 ^, invention description 7 ^ ~~ ) — ^ Cold shot. Referring to Figures 14a-14d, when the scattering bars are around 235 nm4510 nm, a strong scattering bar effect is expected. However, improper placement of the scattering strip near 375 nm * 650 nm will degrade the contrast of the main insulation characteristic image of quadrupole irradiation. If space is provided near the rare characteristics, a second pair of scattering bars can be added. When ring illumination is used, the constructive and destructive structure interactions of the scattering strips will average out a considerable degree, thus greatly reducing the advantages of auxiliary characteristics. Therefore, it is clear from the above that the configuration of the scattering bar is related to the selected irradiation pole. Also know that when multiple scatters are required, their radiation pattern levels should be the same (ie, the radiation pattern should be similar). In short, because of the forbidden space phenomenon and the scattering strip technology is directly caused by the optical interaction between adjacent characteristics, it can be handled and understood in a unified architecture. The above disclosure is related to the phase of the main characteristic field and the phase of the adjacent characteristic field to the irradiation and separation distance. For a given irradiation angle, there are a field phase and a main characteristic field phase 180 which are generated by adjacent characteristics. Out of phase, there is destructive interference between the range. This destructive interference reduces the image contrast of the main characteristics, resulting in loss of exposure range. This forbidden space area is more precisely said that the top interaction space area can be easily handled and determined as detailed above. Interaction distances of the top structures can be obtained to show the corresponding irradiation maps of the better and poorer irradiation areas. Then use the irradiation map as a reference for the irradiation design. When the adjacent characteristic size becomes the size of the scattering bar, similar constructive and destructive interference regions can be found and their corresponding illumination patterns can also be obtained. Based on these illumination patterns, the optimal placement of the scattering strips for a given illumination condition can be determined. Therefore, the position of the scattering bar in this interval is usually the main characteristic field of the main characteristic Gaussian image point and the scattering bar field under the given illumination conditions. When the illumination architecture used changes, the placement of the scattering bar should be adjusted accordingly. When multiple scattering -21 is required-Applicable to China National Standards (CNS) I ^ i ^ 2l0 > < 297mm) ^ 12425 A7 B7 V. Description of invention (19 items, 'their radiation patterns should be similar To achieve maximum benefits.

Although the use of the device according to the present invention in the manufacture of ICS is a specific reference, it should be clearly understood that the device can have many other applications. For example, it can be used in the manufacture of integrated optical systems, the guidance and detection patterns of magnetic domain memory, liquid crystal display panels, and thin-film magnetic heads. Those skilled in the art will understand that in this alternative application, the "main mask,", "wafer," or "die" in this article can be replaced by the more common "mask,", "substrate," and "The target part, replace.

Although the present invention focuses on the lithographic apparatus and method and uses a mask to style the radiation beam entering the projection system, it should be understood that the present invention should be considered here as a lithographic apparatus and a lithographic apparatus that use a general "patterning device" to pattern the radiation beam. Wider content of methods. The term "styled device" used here generally refers to a device that can provide a styled profile corresponding to the pattern generated by entering the Korean beam and the target portion of the substrate. The term "light valve" is also used in this article. This pattern usually corresponds to a device-specific functional layer generated in the target area, such as an integrated circuit or other device. In addition to the mask of the mask table, this styled device includes the following exemplary embodiments. A programmable mirror array. An example of this device is a matrix addressable surface with an adhesive and viscoelastic control layer and a reflective surface. The basic principle of this device is, for example, that the addressing area of the reflective surface reflects incident light as diffracted light, while the unaddressed area reflects incident light as non-diffractive light. With a suitable filter, the reflected beam can filter the non-diffracted light and leave only the diffracted light. In this way, the beam is styled according to the addressing pattern of the matrix-addressable surface. The required matrix addressing can be performed using suitable electronic devices. For more information about this mirror array, please refer to, for example, US patent US 5,296,89 1 -22- This paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 512425 A7 B7 V. Description of the invention (20) and US 5,523,193, incorporated herein by reference. Another example of this device is a programmable LCD array. An example of this architecture can be found in US Patent 5,229,872, which is incorporated herein by reference. As described above, the present invention is far superior to the prior art. More importantly, the present invention provides a method for finding and eliminating the forbidden space region that degrades the overall printing performance, so the CDs and processing range available from the current lithography tools and technologies can be improved. Although specific embodiments of the present invention are disclosed herein, it should be understood that the present invention may be implemented in other forms without departing from the spirit and main characteristics thereof. These examples are therefore to be considered as illustrative and not restrictive, and all changes in the scope and meaning of the scope of the invention as indicated by the scope of the attached patent application and equivalent scope of the patent application are included therein. Explanation of Symbols of Schematic Elements 10 Imaging System 18 Projection Mirror 12 Monochrome Light Source 20 Exit Pupil 14 Concentrator 22 Image Plane 16 Main Mask-23- This paper size applies to China National Standard (CNS) A4 (210 X 297) Mm)

Claims (1)

8 A BCD VI. Application for Patent Scope 1. A method for finding the top interaction space zone, which is used in the design of a photomask to transfer the corresponding lithographic pattern of an integrated device from a photomask to a photomask. The substrate method includes the following steps: (a) determining the irradiation intensity of a first interval and a first irradiation angle, (b) determining the irradiation intensity of the first interval and a second irradiation angle, and the second irradiation angle Rotational symmetry with the first irradiation angle, (c) determining the total irradiation intensity of the first distance by combining the irradiation intensity related to the first irradiation angle and the second irradiation angle, (d) determining the total irradiation intensity Logarithmic slope, and (e) if the derivative of the total log intensity logarithmic slope divided by the first pitch derivative is approximately equal to 0, the first pitch is the top interaction pitch region. 2. If the method of finding the top interaction space zone in item 丨 of the patent application scope includes the following steps: Repeat step (aHe) for multiple different spaces. 3. As for the method of finding the top interaction spacing area in the second patent application scope, the top interaction spacing area is substantially independent of the irradiation angle. 4. For the method of finding the top interaction distance zone, as described in item 丨 of the patent application scope, the second irradiation angle and the first irradiation angle are 90 degrees rotationally symmetric. 5. If the method of finding the top interaction distance zone in item 2 of the scope of patent application, the following steps are also included: For the predetermined top interaction distance: (f) It depends on the predetermined top interaction distance and the first irradiation angle. Irradiation intensity, (g) Irradiation intensity -24 depending on the predetermined top interaction distance and the second irradiation angle -24-This paper is suitable for size _ secret rod (CNS) A4 size (21 ^^ ---- The scope of the patent application 'the second irradiation angle and the first irradiation angle are rotationally symmetric, (h) the second total angle of the predetermined top interaction distance is determined by combining the irradiation intensity related to the first irradiation angle and the second irradiation angle Irradiation intensity, (1) determining the logarithmic slope of the second total irradiation intensity, (j) repeating the step (fHi) for a plurality of different irradiation angles, and (k) if the logarithmic slope of the second total irradiation intensity exceeds a predetermined value , Find out the predetermined irradiation angle corresponding to a non-spacing area. A method for designing an integrated device using a lithographic device to find an unnecessary distance between characteristics when the substrate is formed. The method includes the following steps: (a) determining the irradiation intensity of a first distance and a first irradiation angle, ( b) determine the irradiation intensity of the first distance and a second irradiation angle, the second irradiation angle and the first irradiation angle are rotationally symmetrical, (c) the combination is related to the first irradiation angle and the second irradiation angle The irradiation intensity determines the total irradiation intensity of the first interval, (d) determines the logarithmic slope of the total irradiation intensity, and (e) if the derivative of the logarithmic slope of the total irradiation intensity divided by the first interval derivative is approximately equal to 0, the first The spacing is the top interaction spacing area, and (f) repeats steps (a)-(e) for multiple different spacings; where the top interaction distances found in steps (a)-(f) are: (g ) Determine the top interaction distance and the irradiation intensity of the first irradiation angle, (h) Determine the predetermined top interaction distance and the irradiation of the second irradiation angle -25- This paper applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) The intensity of the scope of the patent application, (i) the combination of the irradiation intensity related to the first irradiation angle and the second irradiation angle to determine the second total irradiation intensity of the predetermined top interaction distance, (J) to determine the second total irradiation intensity Logarithmic slope, (k) repeat steps (g)-(j) for multiple different irradiation angles, and (l) if the logarithmic slope of the second total irradiation intensity exceeds a predetermined value, find and Corresponding to a predetermined irradiation angle. 7. A method for finding an unnecessary distance between characteristics according to item 6 of the scope of patent application, wherein the second irradiation angle and the first irradiation angle are 90 degrees rotationally symmetric. 8 · —A method for finding out the distance between the characteristics when designing the integrated device on the substrate by using the lithographic device, the method includes the following steps: (a) using an irradiation to determine a predetermined irradiation angle within a distance range Intensity, to find the top interaction spacing area; and t (b) determine the top interaction spacing area in step (a) by determining the irradiation intensity of a given top interaction spacing area within an irradiation angle range. Do not space. 9. According to the method of finding the non-spacing between characteristics according to item 8 of the scope of the patent application, the top-interaction spacing zone is defined as a region with substantially constructive optical interference or substantially destructive optical interference. 10. The method for finding the unnecessary distance between characteristics, as described in item 8 of the scope of patent application, wherein the unnecessary distance corresponds to a light intensity exceeding a predetermined value. 11. The method for finding the unnecessary spacing between characteristics, such as the item 10 of the scope of patent application, wherein the unnecessary spacing corresponds to a light intensity exceeding a predetermined value. -26- W2425 Patent Application Range Designing a lithography device using integrated devices to find = Do not use between the characteristics and light correction elements = 20,000 methods include the following steps: Use the edge to determine a predetermined irradiation angle within a range of distance To find the top interaction distance zone; and ~ the intensity of the shot, (b) to determine a predetermined top interaction within a range of irradiation angles <irradiation intensity 'to find the step ⑷ to find the unnecessary distance of each top interaction space zone. 13. The method of finding no space between characteristics according to item 12 of the scope of the patent application, wherein the top interaction space area is defined as a region that has substantially constructive optical interference or substantially destructive optical interference. -27- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)