TW424263B - The polarizing mask for printing the narrow-pitch holes - Google Patents

Abstract

The present invention discloses a kind of polarizing mask for printing the narrow-pitch holes in the optical photolithography process. The polarizing mask includes a transparent substrate, a plurality of first polarizing regions and a plurality of second polarizing regions. The above mentioned first polarizing regions are equally spaced and formed on a transparent substrate. Furthermore, the plurality of first polarizing regions are used to specify the first polarizing direction of the light source. The above mentioned second polarizing regions are formed on top of the first polarizing regions, and one portion of each polarizing region is overlapped with the first polarizing regions. Additionally, the second polarizing regions are allocated in the interval of the first polarizing regions. Furthermore, the plurality of the second polarizing regions are used to specify the direction of the second polarizing regions of the light source, and the angle between the first polarizing regions and the second polarizing regions is used in design to control the amount of light passing through the mask.

Description

424: 2: 6; 3, V. Description of the invention (l) ---- 5 -1 Field of invention: i ί t = Ϊ is related to integrated circuit design, which is particularly related to-a kind of imaging before U shadow In the manufacturing process, a narrow polar hole (narr0w-Pltch h0les) is used to print a polarizing mask (p0iarizing). 5-2 Background of the Invention ...-Manufacturers in the field of circuits have been trying to reduce the size of integrated circuits Element 4 (e.g. transistors or complex gates) has the following advantages in reducing component size: J is more structured. However, when manufacturers try to achieve small and smaller component sizes, the problem of Xu Xi's limitations gradually emerges. Among them, one of the first problems that manufacturers must face is that when looking for smaller components, the precision required for tools used to manufacture integrated circuit components will also increase. Optical lithography is a technique used to transfer patterns onto the surface of a workpiece, just like a semiconductor wafer or a circuit diagram of a wafer, and it can also produce very small and intricate complexities for many other applications. The traditional optical lithography process involves applying electromagnetic radiation (eleCtr〇magnetlc radiati〇n) to a mask, and the 2 masks have openings formed in them. Such a design can make light passing through the openings or The squall line is the m domain on the m surface. Generally, a typical photomask contains a transparent bottom #, and the substrate is

Page 4 212 ^ 2 & 3 V. Description of the invention (2) Computer aided design system (CAD) formulation of various differences: " Two-way two-to-two transfer to, the surface of the wafer = cover = =: completion is visible by , Ultraviolet, or even because the woman transmitted through the photomask to the stone Xi substrate containing a photoresist material. Because the mask first contains a pattern composed of solid lines and light-transmitting spaces, those ranges written only by light-transmitting spaces will allow radiation to pass through. The components on the silicon substrate are created by the above process. The composition of the board is removed on the wafer. The photoresist on the wafer is exposed to appropriate correction and removal. The photoresist is displayed in a separate area. The first Α image shows the area of a mask of chromium. The special photoresist changes the light below the current wavelength, and the photoresist polymerizes the exposed area. Shadow and remove. ), Infinitely small points of light) or chrome (cross-section view of ch, a pattern of holes on a mask with a fixed wavelength will cause a light object to allow the developer (in contrast, the mask is illuminated by the source, where the light is turned off (By chrome rom 1 uni) It allows light to pass through. After a light is exposed to the photoresist polymer with a chemical negative photoresist system, the dot pattern that can be covered by the source 1 1 passes through the photomask to project the resist. The method is divided so that the photoresist structure that is not opened with the mask (with quartz (mask in the coating) is exposed to be cleaned. Each of the traditional photomasks mentioned above is generally referred to as chromium on glass (Chr. me on Glass; COG) or binary mask. The perfect square step function only has the theoretical limit of the exact mask plane. At any distance from the mask, such as the wafer plane, the scattering effect will Causes the image to show a limited image tilt. At a smaller size, that is, the size and distance of the image

Page 5 424263 V. Explanation of the invention (3) The electric field vector of the image near the brush when the relative λ / NA is small will interact with each other and add constructively. The resulting light intensity curve is not completely dark between features' but presents the light intensity generated by the interaction of neighboring features. The resolution of the exposure system is limited to the contrast of the projected light image, that is, the intensity difference between the adjacent bright case features. Increasing the light intensity in the normally dark area will eventually cause adjacent features to print into a superimposed structure rather than a separate image. The first B picture shows the electric field map formed on the photomask. The first C diagram shows an electric field pattern formed on a wafer. The first D picture shows a light intensity map on a circular photoresist film. 1Private course students will often provide a semi-§peripheral phase called the self-decreasing phase shift, which is a difficulty in designing radiation, which usually contains some openings or a phase shift light design. It is used in semiconductor processes. The minimum size of a circuit by optical lithography is usually reduced. Improving the lithographic imaging technology's good resolution 'This results in a reduction in the size and space between the areas of the electromagnetic mask. Recently, a phase shift technique on a lithographic mask, in which a certain part of the mask is phase shifted. Until now, the problem of preventing the introduction of phase shift masks to physically large microcircuits has been that 'for circuit designers, generating a design tool that facilitates the layout of a photomask. For this reason, attenuated phase shifting masks or half-tone phase shifting masks have become another focus. In agricultural subtractive phase shift masks, the

5. Description of the invention (4) A slightly transparent layer is used instead of the chromium layer described above. This mask has the property that there is only one patterning step in the case of a binary mask. The dark areas on the reticle can be phase shifted to 180 degrees and have an attenuating amplitude to prevent too much light from being generated in these areas. Figure A shows a reflective example of the above technique. The combination of the reflective element 20 and the reflective phase shifting element 21 produces a negative amplitude, which provides an improvement in the contrast of the image edges' while attenuation prevents a negative amplitude from becoming a problem. The second diagram B shows the electric field pattern formed on the photomask. The second C diagram shows the electric field pattern formed on the wafer. The second D image shows a light intensity map on the photoresist film of the wafer. Although the attenuating phase shift mask has been widely used to print hole patterns with a larger process window and image contrast than traditional unitary masks, it still has its shortcomings. In particular, due to the wave-like nature of light or other forms of radiation suitable for optical lithography imaging processes, diffraction and other interference influences appear at the edges of the opaque areas of the reticle, which may be in the exposed pattern Changes in scale (or produces misaligned patterns). This phenomenon is clearly shown in the second E diagram, and a ghost pattern 22 is formed in the photoresist layer. 5-3 Objects and Summary of the Invention: In view of the above-mentioned background of the invention, there are many shortcomings caused by the traditional photomask. The invention provides a polarizing mask for printing narrow-pitch holes in optical lithography imaging processes.

42426 3 V. Description of the invention (5) mask), which uses a polarized projection light source to increase the process window, and does not have a side lobe effect. Another object of the present invention is to adjust the polarization direction of a light source by taking advantage of a polarizer. With this operation, the contrast of the precise pattern image can be improved, and therefore the size of the integrated circuit can be reduced. Regarding patterns other than precise one-dimensional patterns, the demand for the degree of micropatterning is relatively low. Therefore, even if the light source polarization is not accurately used in terms of the pattern, the final decay of the contrast is still small. According to the above purpose, the present invention provides a polarizing mask for printing narrow-pitch holes in an optical lithography imaging process. The polarizing mask includes a transparent substrate 'a plurality of first polarizing regions and a plurality of second polarizing regions. The plurality of first polarizing regions described above are formed on a transparent substrate, and 'more' are placed at equal intervals. The plurality of first polarizing regions are used to designate a first polarizing direction of a light source. The plurality of second polarized regions are formed above the first polarized region, and each of the polarized regions has a portion overlapping the position of the first polarized region. In addition, the second polarizing region is disposed at an interval of the first polarizing region, and further, the plurality of second polarizing regions are used to designate a second polarizing direction of the light source. The separation angle between the first polarization direction and the second polarization direction is designed to control the number of light sources passing through the mask.

Page 8 4242.6 3 V. Description of the invention (6) 5-4 Circular simple description: ί-5 Ξ :: a cross-sectional view of a traditional photomask;: a solid electric field on the traditional photomask. Figure 0 shows Form your own picture, when used; The electric field diagram on the circle 'when the traditional photomask is covered by the photomask IS: the light intensity map displayed on the photoresist film of the wafer, when the traditional second B chart shows ί :: ί = sectional view of the shift mask; second. The figure shows the electric field pattern formed on the light shifting mask; when light is shifted, when it is used; 3, the electric field pattern, when the attenuation phase is biased: = = the light intensity diagram on the circular photoresist film, when the attenuation is second Ε circle display-wrong third A picture shows this picture in the photoresist layer; third B picture shows-sectional view of the picture; when the embodiment is used; and "^" photoresist layer, when the fourth embodiment of the invention The figure shows the polarizing angle of the real shell dagger of the present invention, which is not used yet. The representative symbols of the main part: 300 polarizing phase shift light sheet; Quartz substrate; 302 first polarizing region; page 9 ^ 42426 V. Description of the invention (the 303 phase shift region of the 303 second polarized region; 3 1 ◦ photoresist pattern layer; 3 1 1 photoresist; and 3 1 2 photoresist. 5-5 invention detailed description & text, borrow The third A, the third B, and the fourth diagram are used to describe this embodiment in more detail. Please refer to the above-mentioned drawings, especially the third diagram A, which is made according to the present invention. Example of the "Second King of Optical Lithography" used to print narrow-pi tch holes. zing attenuated phase shifting mask). Before entering the details of the preferred embodiment of the present invention, the conventional optical lithography imaging device used in conjunction with the present invention is first introduced. The optical lithography imaging device includes an electromagnetic coupling that emits a partial coupling. A light source of radiation (for example, ultraviolet light). This electromagnetic radiation is applied to the polarizing mask of the present invention. The polarizing mask described above is configured to apply an expected pattern of electromagnetic radiation and transmit through an appropriate optical System, transferred to the surface of a workpiece or wafer. Optical lithography has long been a particularly suitable technology for the transfer of semiconductor components, so it will understand that description will be in that environmental condition. Photoresist

Page 10 4242 ^ 3 V. Description of the invention (8) ’The surface of the workpiece or wafer is covered with a positive or negative photoresist layer. Appropriate photoresistors are well known in the art, so the details are not discussed further here. Subsequently, the aforementioned photoresist layer is selectively engraved "with or without the application of electromagnetic radiation". The surface of the selective area that the electromagnetic wheel strikes is called the electromagnetic radiation appiication region (EAR). An electromagnetic radiation application area is defined as a surface area that has been exposed to sufficient electromagnetic radiation from an influential light source. And any surface area that is not within the application area of the electromagnetic wheel is defined as an unaffected space. The polarizing phase shifting mask 300 of the present invention includes a transparent substrate 30, which is a transparent substrate. Quartz material is particularly preferred, a plurality of first subpolar regions 3 002, a plurality of second subpolar regions 3 303, and a non-mandatory (optional or optional) phase offset region 304. The first polarizing region 302 is formed on the quartz substrate 301 and is placed at equal intervals. Furthermore, the plurality of first polarization regions are used to designate a first polarization direction of a light source. The plurality of second polarized regions 303 are formed above the plurality of first polarized regions 302, and each of the plurality of first polarized regions has a portion and the positions of the plurality of first polarized regions are repeated . Furthermore, the plurality of second polar regions are designed

V. Description of the invention (9) It is placed at intervals in a plurality of first polarization regions, and is mainly used to specify a second polarization direction of the light source. The above-mentioned optional phase shift region 304 is subordinated to the overlapping position of the first polar region and the second polar region, and is between the first polar region and the first polar region.

In addition, each of the plurality of second polarized regions 3 0 3 is formed in a T-shaped structure and is also placed at equal intervals, and has a first thickness at the overlapping position, and a second thickness at At intervals in the plurality of first polarization regions 302. The thickness of the first polarized region is approximately the same as the thickness of the second polarized region, and the width of the interval in the plurality of second polarized regions is equal to the width of the interval in the plurality of first polarized regions. Nonetheless, the equal interval width of the first and second polarized regions and the equal interval of the first or second polarized regions are specifically designed for hole patterns of a fixed pitch (f i X e d p i t c h). These restrictions can be changed or redesigned with different patterns.

In any case, the present invention is used to design the above-mentioned limitation of the phase-shifting phase shift mask 300, and finally the patterned photoresist layer 310 shown in FIG. 3B is generated. Here, the required resolution of the photoresist pattern 310 is reduced from the conventional distance 1 (the distance between the photoresist 311 and 312 generated in different polarized regions) to the distance 2 in the present invention (the photoresist generated in the same polarized region). Distance between 3 and 11). In other words, to make high-density components, the present invention only requires a lower resolution than in general.

Page 12 4-24263 V. Description of the Invention Finally, the first polarizing direction of the first polarizing region and the second polarizing direction of the second polarizing region are less than 90 degrees in the design of the separation angle. This separation angle is designed to control the number of light sources passing through the polarizing mask. The fourth figure shows the polarization angle used in the embodiment of the present invention. The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the patent application for the present invention; all other equivalent changes or modifications made without departing from the spirit disclosed in the present invention 2 should be included in the following Within the scope of patents. please

Page 13

Claims (1)

Compared with 4ί.2β'3: VI. Patent Application Scope 1 · A kind of optical narrow-ρχ tch mask containing at least a plurality of first polarized region areas is used to refer to a plurality of first squares', and the plurality of copies and the The plurality of regions are set in a plurality of second sub-lithographic imaging processes and used to print a pol ar i zi ng mask with a narrow pitch hole (ho 1 es). One transparent region of the transparent substrate is formed in The plurality of transparent substrates are placed at equal intervals, and further, the plurality of first polarized poles define a first polarized direction of a light source; and the two polarized regions are formed on the plurality of first polarized regions. Each of the two polarized regions has a first partial polarized region overlapping, the plurality of second polarized regions and the plurality of first polarized regions spaced apart, and the polar region is used to designate a first polarized region of the light source. The light-shielding material between the bipolar directions to 3. The reticle according to item 1 of the scope of patent application, wherein the above-mentioned transmission rarely includes quartz. 4. The reticle according to item 1 of the scope of patent application, wherein the design of the separation angle between the first-polarizing direction and the second polarizing direction is smaller than M degrees. Page 14 424263 VI. Patent application scope ~-5. For example, the photomask of item 4 of the patent application scope, wherein the above-mentioned separation angle is designed to control the number of light sources passing through the light army. 6. For example, the reticle of item 1 of the patent application scope, wherein the part of the plurality of second subpolar regions and at least one of the first subpolar regions are located at #. 7. The reticle according to item 1 of the scope of patent application, wherein each of the plurality of-polarized regions described above is formed with a -D structure, and has a first thickness at the overlapping position, and-the second The thickness is at intervals in the plurality of first polar regions. The description of the first number is its cover. Item 1 is placed in the first compartment. Fan et al. Specializes in the field φ-zone such as pole 8. points 9. A polarized phase used to print narrow-pitch holes in the optical lithography imaging process A polizing phase shifting mask, the mask at least comprises: a quartz substrate; a plurality of first polarized regions are formed on the quartz substrate, and the plurality of first polarized regions are placed at equal intervals Furthermore, the plurality of first polarization regions are used to designate a first polarization direction of a light source; the plurality of second polarization regions are formed over the plurality of first polarization regions', and the Each polarized region has a portion that overlaps with the positions of the plurality of first polarized regions, and the plurality of second polarized regions Page 15 424: ^ 6 3 VI. The patent application area is the interval set in the plurality of first polarized regions, and the plurality of second polarized regions are used to specify a second polarized direction of the light source. And a phase offset region is formed at the overlapping position and is between the first and second polarized regions. 10. The reticle according to item 9 of the scope of patent application, wherein the design of the separation angle between the first polarization direction and the second polarization direction is less than 90 degrees. Q 11. The reticle according to item 10 of the scope of patent application, wherein the above-mentioned separation angle is designed to control the number of times the light source passes through the reticle. 1 2. The reticle according to item 9 of the scope of patent application, wherein the portion of the plurality of second subpolar regions described above overlaps with at least one of the first subpolar regions. 1 3. The reticle according to item 9 of the scope of patent application, wherein each of the plurality of second polarized regions is formed in a T-shaped structure having a first thickness at the overlapping position, and a first Two thicknesses are at intervals in the plurality of first polar regions. 14. The reticle according to item 13 of the scope of patent application, wherein the thickness of the first polarized region is approximately equal to the first thickness of the second polarized region. 1 5. If the photomask of item 9 of the patent application scope, wherein the plurality of second Page 16 4242 β 3 VI. Scope of patent application The polarized regions are placed at equal intervals. 16. The reticle according to item 15 of the scope of patent application, wherein the width of the interval in the plurality of second polarized regions is equal to the width of the interval in the plurality of first polarized regions. G Page 17