TW567390B - Method for improving photo mask quality - Google Patents

Abstract

This invention provides a method for improving photo mask quality by removing non-transparent particles in the openings of the pattern on the photo mask. Firstly, a pattern opening is formed in a non-transparent layer on a transparent substrate, in which the bottom of the pattern opening has non-transparent particles. Then, a negative photo resist layer is formed in the pattern opening to cover the non-transparent particles. After the formation of the negative photo resist layer, a back side exposure process is carried out on the transparent substrate and a development process is performed to remove the portion of the negative photo resist layer which is not exposed. Subsequently, the residual negative photo resist layer is used as a mask to remove the non-transparent particles from the top side of the transparent substrate. Finally, the residual negative photo resist layer is removed.

Description

567390 V. Description of the invention α) Field of the invention: The present invention relates to a method for removing opaque particles on a transparent substrate of a photomask to improve the quality of photomask production, and in particular, to sequentially perform negative photoresist coating and Back exposure procedure and related methods for removing opaque particles to prevent the formation of a river bed effect on the upper surface of a transparent substrate. Background of the Invention: With the rapid development of electronic technology, the size of electronic components is gradually shrinking. In the technology of making these components, the development of exposure imaging and etching technology has a significant impact. Therefore, in addition to the current demand for the development of electronic technology, in addition to the advantages of fast speed, low power consumption, and high packaging density, the speed and reliability of all processes have also received more attention from the semiconductor industry. The above-mentioned exposure imaging technology can also be collectively referred to as lithography technology. This technology is not only one of the important key technologies of the entire semiconductor industry. Because the patterns and doping regions of the semiconductor thin films are also This technology determines it, so it plays the most important role. For example, when you want to make metal inter-connections on a semiconductor substrate, you must first prepare a photo mask with the desired metal interconnect pattern, and then use a spin coating. Spin coating is used to form a photoresist layer with photosensitivity on the semiconductor substrate. When the parallel light from the light source passes through the photomask and the lens, it will be irradiated on the photoresist layer ’, which will form the same pattern as the metal interconnects on the photomask, but it has been transmitted through.

JO / 390 photoresist layer. In other words, the pattern is complete and small ’in order to effectively improve the accuracy, it looks very concealed. The mask is made of "of course, the main material used by it". However, at present, almost all the drawings written on the surface of glass 10 can choose chromium (Cr). 5. Description of the invention (2) The mirror-reduced figure is in this formula. The photoresist can be placed on the photoresist layer. Based on the above reasons, the photomask pattern is refined. This figure reveals one of the traditional light quartz glass 10. There are currently three more commonly used hoods and quartz glass. Next, in quartz / idea, semiconductor 1 2 is used. In general, it is important to say that it is important to transfer the entire semiconductor process yield using such a method. Please refer to the first picture. The main body of is made of flat and transparent material. It is not only quartz glass that has soda glass and emulsion light has been replaced by quartz glass.上 Lower layer of metal 12. It is worthwhile that all are formed on this metal layer as the material of the metal layer 12. The following is a detailed introduction to the formation of the desired pattern in the chrome metal layer. ° First, the pattern of the pattern is formed by means of laser light or electron beam. Exposed on the road metal layer. This exposure concept is actually the same as that of a photo. The difference is that in the manufacturing technology of a semiconductor mask, the pattern shape is exposed on a chrome metal layer using laser light or an electron beam in an exposure machine. Subsequently, as long as the developer uses the developer to display the shape of the pattern in the chrome metal layer, and then use etching and other techniques to etch away part of the pattern, the chrome metal layer can be formed as shown in the second figure Need pattern opening 14. Please refer to the third figure later. When the chromium metal layer is etched, metal debris 16 is likely to remain or fall in the pattern opening 14. Therefore, a focus ion beam is used in the manufacturing process. beam)

567390 V. Description of the invention (3) To remove the metal chips 16 to avoid the subsequent use of this mask as a mask to form a pattern in a semiconductor substrate, which will reduce the accuracy of pattern making. Please refer to the fourth figure. When the metal debris is removed by the impact of the electron beam, a portion of the upper surface of the quartz glass located on the side of the metal debris will be injured and a so-called riverbed effect will be formed. 18 'As a result of the subsequent pattern definition of the semiconductor substrate with this mask as a mask', the accuracy is reduced, which in turn greatly affects the process yield. OBJECTS AND SUMMARY OF THE INVENTION: The main object of the present invention is to provide a method for forming a #etched mask power layer using a material characteristic of negative photoresist to remove opaque particles in a transparent substrate. Another object of the present invention In order to provide a method for removing the metal particles of the photomask, a method of forming an etch mask power layer by using the characteristics of a negative photoresist material to avoid the river bed effect of the glass substrate. Another object of the present invention is to provide an etching mask layer on the bottom surface of the pattern opening that is not covered by the metal particles, so as to prevent gallium atoms from being deposited on the upper surface of the glass substrate after the metal particles are subsequently removed. A method of avoiding the river bed effect during the removal of the metal particles of the mask. First, a pattern opening is formed in the metal layer on the upper surface of the glass substrate to expose part of the upper surface of the glass substrate.

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The bottom surface will have metal particles that have not been removed. ㈣ = metal layer Λ ′ and covers the pattern opening and metal particles. Negative = After the formation, the glass substrate is subjected to an exposure process, that is, a development process, to remove a portion of the metal layer and the positive particles of the metal particles =: a negative photoresist layer. The non-removed negative photoresist layer is defined as an etch mask power layer. Finally, the metal particles are subjected to an etching removal process from the front side of the glass substrate. When the engraving process is complete, remove the money engraving mask power layer. Detailed description of the invention:

The invention discloses a method for avoiding a riverbed effect on a transparent substrate during the process of removing opaque particles. First, an opaque layer is formed on a transparent substrate. In a preferred embodiment, the opaque layer may be a metal layer, and the transparent substrate may be a mask substrate. Generally, the material of the mask substrate can be selected from soda glass, emulsion mask and quartz glass. Next, referring to the fifth figure, a pattern opening 54 is formed in the metal layer 5.2 to expose a part of the upper surface of the glass substrate 50. Before the pattern opening 54 is formed, a spin coating method may be performed to form a photoresist layer on the upper surface of the metal layer 52 (not shown in the figure), and then transfer the designed desired pattern to the photoresist layer. To form a desired pattern therein. Then please continue to refer to the fifth figure, and use the photoresist layer with the desired pattern opening as a mask to perform the engraving process on the metal layer 52 to form the pattern opening 54 in the metal layer 52. After the etching process, The bottom surface of the pattern opening 5 4 is apt to have metal particles 5 6 that are not attached or dropped (as shown in the sixth figure). Then refer to the seventh figure to perform the coating process to form a negative

Page 7 567390 V. Description of the invention (5) The photoresist layer 58 is on the metal layer 52 'and fills the pattern opening 54 and the covering metal particles 56. It is worth noting that the negative photoresist layer 58 will have a cross-linking reaction after being exposed to light, which will strengthen its structure without dissolving in the developer. After the negative photoresist layer 58 is formed, it is sequentially exposed from the back of the glass substrate 50 to strengthen the structure of the exposed area 60 (that is, the area not covered by part of the metal layer 52 and the metal particles 56). Next, referring to the ninth figure, a developer is used to remove a portion of the negative photoresist layer 62 ′ that is not exposed and define the negative photoresist layer remaining on the bottom surface of the pattern opening 54 that is not covered by the metal particles 56 as the power layer of the engraved mask. 64. After the lithographic mask layer 64 is formed, the metal particles 56 are subjected to an etching removal process from the front surface of the glass substrate 50. It is worth noting that, because the etch mask power layer 64 has covered the surface on the side of the metal particles 56: part of the glass substrate 50, the metal particles 56 are subjected to physical impact as a surname engraving procedurea The upper surface of the glass substrate 50 covered by the curtain layer of money carved grass is also protected from damage by the above-mentioned forces, thereby preventing the occurrence of the river bed effect. When the etching is completed, the etching mask layer 64 is removed. 70 The manufacturing quality of the photomask has a crucial and decisive influence on the formation of subsequent patterns required by the semiconductor, that is, when the defects of the photomask cannot be effectively removed, it will make the semiconductor When the pattern is defined, the process yield is severely reduced. For example, when a photomask with a river bed effect is used as a mask power, it is easy to produce a desired connection between the various patterns in the semiconductor substrate when the semiconductor substrate is exposed to the exposure process. The purpose of the present invention is to remove The metal particles in the photomask, = 567390 V. Description of the invention (6) The production quality of the high photomask and the yield of subsequent processes. In addition, after the fabrication of the photomask, in order to detect defects located there, 'gallium (Ga) ions will be used to scan the defect location'. Because during the scanning process, gallium ions will be deposited on the glass substrate. The upper surface causes the transmittance of the glass substrate to decrease, and after completion of the subsequent defect removal step, additional procedures are required to further remove gallium ions. By using the method of the present invention, forming a negative photoresist layer on the surface of a portion of the glass substrate on the side of the defect can greatly reduce the chance of gallium ions directly contacting the glass substrate. Although the present invention is explained as above with a preferred example, it is not intended to limit the spirit and the inventive substance of the present invention, but only to this embodiment. It is considered that all modifications made without departing from the spirit and scope of the present invention should be included in the scope of patent application described below. · _

567390 Schematic illustrations Schematic illustrations: ^ The above detailed description and the many advantages of this invention can be easily understood through the following detailed description combined with the attached drawings, where: The first figure is a cross-sectional view of the photomask , Which shows the composition of the photomask material currently used in the industry. The second figure is a cross-sectional view of the mask, showing the steps of making a pattern opening in the metal layer according to the current industry technology. The third figure is a cross-sectional view of the photomask, showing according to the current industry. The step of technically generating metal particles on the bottom surface of the pattern opening; the fourth figure is a cross-sectional view of the photomask, which shows the situation of the river bed effect according to the current industry technology; the fifth figure is the cross-sectional view of the photomask, showing the patterned opening made according to the present invention The step in the metal layer; the sixth figure is a cross-sectional view of the photomask, showing the steps of generating metal particles on the bottom surface of the pattern according to the present invention; the seventh figure is the cross-sectional view of the photomask, showing the coating according to the present invention The step of arranging a negative photoresist layer on the metal layer and covering the pattern openings and the metal particles; Exposing a back glass substrate of the step; and a cross-sectional view of a ninth picture shows a photomask, a display step portion of the photoresist layer not removed traced light of the present invention. Drawing number comparison table:

Page 10 567390 Schematic illustration of quartz glass 1 0 pattern opening 1 4 river bed effect 1 8 metal layer 5 2 metal particles 5 6 exposed area 60 money mask power layer 6 4 metal layer 12 metal debris 1 6 glass bottom 50 Pattern opening 5 4 Negative photoresist layer 5 8 Part of the negative photoresist layer that has not been exposed 6 2

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Claims (1)

567390 VI. Application for Patent Scope 1. A method of removing opaque particles in a pattern opening to improve a mask product. 'First, a pattern opening is formed in an opaque layer on a transparent substrate, and the pattern opening is The bottom surface has opaque particles, and the method includes at least the following steps: forming a negative photoresist layer in the pattern opening and covering the opaque particles; performing a back exposure procedure on the transparent substrate; removing unexposed portions of the A negative photoresist layer; removing the opaque particles with a portion of the negative material remaining after the exposure; and ㈢ as a mask, the remaining negative photoresist layer is removed by the transparent bottom. 2. If Fangying glass is applied for item 丨 in the scope of patent application. Among them, the transparent substrate mentioned above is stone 3 · As the conductive substrate of item 丨 of the scope of patent application. Among them, the above-mentioned transparent substrate is half-four. The method of applying for item 1 of the patent scope makes the above-mentioned opaque layer to be gold. , Which makes the above-mentioned opaque micro-particles to 6 · — a method to improve the quality of the light army, used to remove the metal particles of the photomask over 567390 6. In the process of applying for a patent, the method of avoiding the river bed effect is to first form a metal layer which is opened on the upper surface of the glass substrate to expose part of the upper surface of the glass substrate, and the bottom of the pattern opening The surface has metal particles that have not been removed. The method includes at least the following steps: coating a negative photoresist layer on the metal layer and covering the pattern opening and the metal particles; the negative light is exposed from the back of the glass substrate The resist layer is subjected to an exposure process; the negative photoresist layer located above the part of the metal layer and the metal particles is removed, and an etching mask power layer is formed on the bottom surface of the pattern opening that is not covered by the metal particles; An etching process is performed on the front surface of the glass substrate to remove the metal particles; and the etching mask layer is removed. Among them, the material of the above glass substrate f • If the method in the scope of patent application No. 6 is quartz >. 8 · —A method for improving the quality of a photomask provides a transparent substrate; the method includes at least the following steps: a metal layer is deposited on the transparent substrate; and the exposed portion is etched to define the opening pattern at 1 COSCO The upper surface of the transparent substrate; 〃 coating a negative photoresist on the transparent substrate, performing back exposure on the transparent substrate, and filling the opening pattern with the bottom of the opening pattern 567390, patent application scope-when there are metal particles, the metal particles located on the metal particles will not be exposed; otherwise, the negative photoresist will be developed to remove the unexposed part of the negative photoresist; An etching process is performed on the remaining metal particles by using a portion of the negative photoresist remaining in the opening pattern as an etching mask to remove it. 9. If item 8 of the scope of patent application, the towel is quartz. 〇〇 之 方 沄, a material with a transparent substrate as described above