Photomask and forming method thereof
By forming a blocking layer on the photomask to isolate the exposure energy, the problem of photoresist residue is solved, the reliability and lifespan of the photomask are improved, and the risk of manually removing residual photoresist is reduced.
Patent Information
- Application Number
- CN202410580573.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-10
- Publication Date
- 2025-11-11
AI Technical Summary
Existing photomasks are prone to producing a large amount of photoresist residue after long-term exposure, and the manual removal of the residue is dangerous and inefficient, resulting in a high risk of photomask scrapping.
A blocking layer surrounding the marking area is formed on the transparent substrate of the photomask. The blocking layer material is metallic chromium with 0% transmittance and 100% reflectance. It is formed by physical sputtering. The blocking layer has a width of 2-3 mm and a thickness of 40 nm-50 nm. It is used to isolate exposure energy and reduce the stickiness of the adhesive layer.
It effectively reduces photoresist residue, minimizes the generation of residual photoresist, avoids the danger of manually removing residual photoresist, and improves the lifespan and reliability of the photomask.
Smart Images
Figure CN120928644A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and in particular to a photomask and a method for forming the same. Background Technology
[0002] A photomask uses quartz glass as a substrate, on which a layer of chromium metal and photosensitive emulsion are plated to form a photosensitive material. The designed circuit pattern is exposed onto the photosensitive emulsion using an electronic laser device, and the exposed area is developed to form the circuit pattern on the chromium metal.
[0003] After a photomask is shipped from the photomask manufacturer, it undergoes exposure at the wafer foundry. The purpose of this exposure is to project the pattern on the photomask onto the photoresist on the wafer, achieving photolithography. However, prolonged exposure times or exposure cycles can excite sulfate ions within the photomask, forming a large amount of ammonium sulfate crystals (called haze). Haze affects light transmittance. Therefore, photomasks with haze need to be recalled for remounting to remove the haze. However, after prolonged exposure, a large amount of waste photoresist remains on the photomask during remounting, especially on the contact surface with the quartz glass. Current cleaning equipment has insufficient capacity for removing this waste photoresist, and manual removal is prone to improper operation, easily leading to photomask failure and significant losses. Therefore, finding a solution to this waste photoresist residue at its source is an urgent research topic.
[0004] Furthermore, engineers manually remove residual adhesive using cotton swabs soaked in the organic solvent acetone. This process is time-consuming and uses acetone, which is extremely harmful to human health. It also requires very strict operating procedures from engineers and carries a certain risk of failure. Summary of the Invention
[0005] This application provides a photomask and a method for forming the same, which can avoid the generation of a large amount of photoresist residue after long-term exposure of the photomask.
[0006] One aspect of this application provides a photomask, comprising: a transparent substrate, the transparent substrate including a patterned area and a blank area, the blank area being disposed around the patterned area, the patterned area including a main patterned area and a marking area disposed around the main patterned area;
[0007] A blocking layer is located on the surface of the blank area and surrounds the marked area. The light transmittance of the blocking layer is 0%, and the light reflectance is 100%.
[0008] In some embodiments of this application, the surface of the blocking layer further includes an adhesive layer and a frame, the width of the frame being less than or equal to the width of the blocking layer, and the adhesive layer being used to adhere the frame to the blocking layer.
[0009] In some embodiments of this application, the thickness of the blocking layer is greater than or equal to the thickness of the pattern layer formed by the graphic area.
[0010] In some embodiments of this application, the blocking layer material is metallic chromium.
[0011] In some embodiments of this application, the width of the blocking layer is 2-3 mm, and the thickness of the blocking layer is 40 nm-50 nm.
[0012] Another aspect of this application provides a method for forming a photomask, comprising: providing a transparent substrate, the transparent substrate including a patterned area and a blank area, the blank area being disposed around the patterned area, the patterned area including a main patterned area and a marking area disposed around the main patterned area; forming a blocking layer on the surface of the blank area, the blocking layer being disposed around the marking area, the blocking layer having a light transmittance of 0% and a light reflectance of 100%.
[0013] In some embodiments of this application, the method further includes: bonding a frame to the surface of the blocking layer with an adhesive layer, wherein the width of the frame is less than or equal to the width of the blocking layer, and the adhesive layer is used to bond the frame to the blocking layer.
[0014] In some embodiments of this application, the blocking layer material is metallic chromium.
[0015] In some embodiments of this application, the method for forming the blocking layer includes physical sputtering.
[0016] In some embodiments of this application, the width of the blocking layer is 2-3 mm, and the thickness of the blocking layer is 40 nm-50 nm.
[0017] The photomask and its formation method provided in this application form a blocking layer surrounding the marked area by depositing a blocking layer on the transparent substrate of the photomask. The blocking layer is opaque and has high reflectivity. By utilizing the physical characteristics of low penetration and high reflection of the blocking layer, the energy transmission barrier on the adhesive layer is blocked during exposure, thereby reducing the adhesive's stickiness and reducing residual adhesive.
[0018] Optionally, the blocking layer overlaps with the pellicle to minimize other impacts on the mask. Attached Figure Description
[0019] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale.
[0020] in:
[0021] Figure 1 This is a schematic diagram of a planar structure of a photomask;
[0022] Figure 2 This is a schematic diagram of the frame position structure of a photomask.
[0023] Figure 3 This is a schematic diagram showing the position of light rays within the frame of the photomask during exposure.
[0024] Figure 4 This is a schematic diagram of the structure of a photomask according to an embodiment of this application;
[0025] Figure 5 For the appendix Figure 4 A schematic diagram of the cross-sectional structure along the AA direction;
[0026] Figure 6 For the appendix Figure 4 A schematic diagram of the cross-sectional structure after adding an adhesive layer and a frame along the AA direction;
[0027] Figure 7 for Figure 6 Schematic diagram of the cross-sectional structure in the middle BB direction;
[0028] Figure 8 In order to expose the light at Figure 6 Schematic diagram of the cross-sectional structure in the middle BB direction; Detailed Implementation
[0029] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.
[0030] Appendix Figure 1This is a schematic diagram of a planar structure of a photomask. The photomask includes a transparent substrate 10, which includes a patterned area and a blank area 13. The patterned area includes a main patterned area 11 and a marking area 12. The main patterned area 11 is used to form the main pattern of the photomask, and the marking area 12 is used to form a marking pattern. The blank area does not form a pattern and is the bare surface of the transparent substrate. A frame 14 is formed around the marking area. A protective film is formed on the frame 14 to protect the patterned area and prevent dust from contaminating it. The frame can be bonded to the transparent substrate with acrylic adhesive. A partial cross-sectional schematic diagram of the frame, acrylic adhesive, and transparent substrate is shown below. Figure 2 As shown, acrylic adhesive 15 and a frame 14 are stacked sequentially on the transparent substrate 10. During exposure, as... Figure 3 As shown, light enters the interior of the acrylic adhesive 15 from the transparent substrate 10. Since the acrylic adhesive 15 is generally made of a high molecular polymer, it is relatively sensitive to energy. When the light energy enters the acrylic adhesive 15 during exposure, it will exacerbate the breakage of the carbon chains in the high molecular polymer, thereby destroying the overall structure of the acrylic adhesive 15, enhancing the adhesion between the acrylic adhesive 15 and the transparent substrate, and increasing the probability of adhesive residue.
[0031] After prolonged exposure, a large amount of waste adhesive remains on the surface of the transparent substrate during remounting of the photomask, which is difficult to remove. Therefore, this application provides a photomask comprising: a transparent substrate, the transparent substrate including a patterned area and a blank area, the blank area surrounding the patterned area, the patterned area including a main patterned area and a marking area surrounding the main patterned area; and a blocking layer located on the surface of the blank area, surrounding the marking area, the blocking layer having 0% light transmittance and 100% light reflectance.
[0032] The blocking layer is disposed on the surface of the blank area and surrounds the marking area. The light transmittance of the blocking layer is 0%, and the light reflectance is 100%. That is to say, when exposed, the light energy is reflected on the surface of the blocking layer after passing through the transparent substrate and cannot enter the interior of the acrylic adhesive layer. Even after multiple exposures, no residue will remain on the surface of the transparent substrate.
[0033] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.
[0034] Figure 4 This is a schematic diagram of the planar structure of a photomask provided in an embodiment of this application. Figure 2 For along Figure 5 Cross-sectional view created by the dashed line.
[0035] refer to Figure 4 and Figure 5 As shown, a photomask includes: a transparent substrate 101, the transparent substrate 101 including a patterned area 110 and a blank area 120 surrounding the patterned area 110, the patterned area 110 including a main patterned area 1101 and a marking area 1102 surrounding the main patterned area 1101; and a blocking layer 102, the blocking layer 102 being located on the surface of the blank area 120 and surrounding the marking area 1102, the blocking layer 102 having a light transmittance of 0% and a light reflectance of 100%.
[0036] When performing the exposure step in the photolithography process using the photomask 100, the patterned area 110 is the exposure area. Those skilled in the art will understand that, due to the presence of the mask pattern, some areas of the patterned area can be penetrated by light, while others cannot, depending on the design structure of the mask pattern. In some embodiments of this application, a chromium layer is formed on the surface of the areas that cannot be penetrated by light.
[0037] In this embodiment of the application, the graphic area 110 includes a main graphic area 1101 and a marking area 1102. The main graphic area is used to form a chip and includes several chip areas and areas such as dicing channels for separating the chip areas and dividing the chip.
[0038] The marking area 1102 is used to form a marking pattern, such as a marking indicating the chip type or model, or an alignment mark. The marking area 1102 can also form different patterns depending on the marking pattern. The blank area 120 does not participate in the exposure process and is typically the bare substrate of the transparent substrate.
[0039] In the marking area 1102, apart from the area with the designed marking pattern, the other areas are made of light-blocking material, which prevents exposure light from passing through during the exposure process.
[0040] In some embodiments of this application, the transparent substrate 301 is made of, for example, quartz glass. Since the transparent substrate 301 is a transparent material, it allows light of any wavelength to pass through. Therefore, the blank area allows light of any wavelength to pass through.
[0041] In this embodiment, the blocking layer 102 is located on the surface of the blank area 120 and surrounds the marking area 1102. The light transmittance of the blocking layer 102 is 0%, and the light reflectance is 100%. That is, the blocking layer 102 is a material capable of blocking light, such as a metal material. In some embodiments of this application, the metal material is chromium.
[0042] The width of the blocking layer 102 ranges from 2 to 3 mm, and the thickness ranges from 40 nm to 50 nm. The width of the blocking layer 102 is greater than the width of the adhesive layer to prevent exposure energy from entering the adhesive layer. The thickness of the blocking layer 102 is greater than or equal to the thickness of any pattern layer formed in the patterned area to avoid affecting the quality of the film layer.
[0043] Reference Appendix Figure 6 and attached Figure 7 As shown in some embodiments of this application, the surface of the blocking layer further includes an adhesive layer 105 and a frame 104, the width of the frame 104 being less than or equal to the width of the blocking layer 102, and the adhesive layer 105 being used to adhere the frame 104 to the blocking layer 102.
[0044] The adhesive layer 105 is made of, for example, an acrylic polymer, with a thickness of less than 1 mm and a width the same as that of the blocking layer 102.
[0045] In this embodiment, the frame 104 can be an aluminum alloy frame, which is adhered to the blocking layer 102 by the adhesive layer 105. The width of the frame 104 is less than or equal to the width of the blocking layer 102, and the width ranges from 1 to 2 mm. In some embodiments of this application, the blocking layer 102 has a width of 2.5 mm and a thickness of 45 nm, and the frame 104 has a thickness of 2 mm and a width of 1.5 mm.
[0046] A protective film is formed on the frame 104 to provide overall protection for the graphic area and prevent the graphic area from getting dusty.
[0047] When performing an exposure process using the photomask, such as Figure 8 As shown, when light reaches the blocking layer 102 from the transparent substrate 101, the light is reflected from the surface of the blocking layer 102 because it is an opaque material. Therefore, the energy from the exposure does not enter the adhesive layer 105, preventing the adhesive layer 105 from being damaged or adhering to other materials. Furthermore, the blocking layer 102 also isolates the adhesive layer 105 from direct contact with the transparent substrate 101, avoiding adhesion between them.
[0048] This application embodiment also provides a method for forming a photomask, comprising: providing a transparent substrate, the transparent substrate including a patterned area and a blank area, the blank area being disposed around the patterned area, the patterned area including a main patterned area and a marking area disposed around the main patterned area; forming a blocking layer on the surface of the blank area, the blocking layer being disposed around the marking area, the blocking layer having a light transmittance of 0% and a light reflectance of 100%.
[0049] The method for forming the blocking layer includes physical sputtering. The blocking layer can also be formed directly through pattern design during the patterning process of the patterned area. In some embodiments of this application, the width of the blocking layer is 2-3 mm, and the thickness of the blocking layer is 40 nm-50 nm. In some embodiments of this application, the blocking layer material is metallic chromium. The width of the blocking layer 102 is greater than the width of the adhesive layer to prevent exposure energy from entering the adhesive layer. The thickness of the blocking layer 102 is greater than or equal to the thickness of any patterned layer formed in the patterned area to avoid affecting the quality of the film layer.
[0050] In some embodiments of this application, the method further includes: bonding a frame to the surface of the blocking layer using an adhesive layer, wherein the width of the frame is less than or equal to the width of the blocking layer, and the adhesive layer is used to adhere the frame to the blocking layer. The process of bonding the frame to the surface of the blocking layer can be performed using a laminating machine.
[0051] The adhesive layer 105 is made of, for example, an acrylic polymer, with a thickness of less than 1 mm and a width the same as that of the blocking layer 102.
[0052] In this embodiment, the frame 104 can be an aluminum alloy frame, which is adhered to the blocking layer 102 by the adhesive layer 105. The width of the frame 104 is less than or equal to the width of the blocking layer 102, and the width ranges from 1 to 2 mm. In some embodiments of this application, the blocking layer 102 has a width of 2.5 mm and a thickness of 45 nm, and the frame 104 has a thickness of 2 mm and a width of 1.5 mm.
[0053] A protective film is formed on the frame 104 to provide overall protection for the graphic area and prevent the graphic area from getting dusty.
[0054] The photomask and its formation method provided in this application involve depositing a blocking layer around the marked area on a transparent substrate of the photomask. This blocking layer is opaque and has high reflectivity. Utilizing the low transmittance and high reflectance properties of the blocking layer, the energy transmission barrier on the adhesive layer is blocked during exposure, thereby reducing the adhesive's stickiness and minimizing residue. Optionally, the blocking layer overlaps with the pellicle to minimize other impacts on the photomask.
[0055] In summary, after reading this application, those skilled in the art will understand that the foregoing application content is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that this application is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are all within the spirit and scope of the exemplary embodiments of this application.
[0056] It should be understood that the term "and / or" as used in this embodiment includes any or all combinations of one or more of the associated listed items. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element.
[0057] Similarly, it should be understood that when an element such as a layer, region, or substrate is referred to as being "on" another element, it may be directly on that other element, or there may be intermediate elements present. Conversely, the term "directly" means without intermediate elements. It should also be understood that the terms "comprising," "including," "including," or "comprises," as used in this application, indicate the presence of the described features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.
[0058] It should also be understood that although the terms first, second, third, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, without departing from the teachings of this application, a first element in some embodiments may be referred to as a second element in other embodiments. The same reference numerals or the same reference signs denote the same elements throughout the specification.
[0059] Furthermore, this application specification describes exemplary embodiments by referring to idealized exemplary cross-sectional views and / or plan views and / or perspective views. Therefore, differences from the illustrated shapes are foreseeable due to factors such as manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but should include deviations in shape caused, for example, by manufacturing processes. For instance, etched areas shown as rectangular typically have circular or curved features. Therefore, the regions shown in the figures are substantially schematic, and their shapes are not intended to illustrate the actual shape of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.
Claims
1. A photomask, characterized in that, include: A transparent substrate, the transparent substrate including a patterned area and a blank area, the blank area being disposed around the patterned area, the patterned area including a main patterned area and a marking area disposed around the main patterned area; A blocking layer is located on the surface of the blank area and surrounds the marked area. The light transmittance of the blocking layer is 0%, and the light reflectance is 100%.
2. The photomask as described in claim 1, characterized in that, The surface of the blocking layer also includes an adhesive layer and a frame, the width of which is less than or equal to the width of the blocking layer, and the adhesive layer is used to adhere the frame to the blocking layer.
3. The photomask as described in claim 1, characterized in that, The thickness of the blocking layer is greater than or equal to the thickness of the pattern layer formed by the graphic area.
4. The photomask as described in claim 1, characterized in that, The blocking layer material is metallic chromium.
5. The photomask as described in claim 1, characterized in that, The width of the blocking layer is 2mm to 3mm, and the thickness of the blocking layer is 40nm to 50nm.
6. A method for forming a photomask, characterized in that, include: A transparent substrate is provided, the transparent substrate including a patterned area and a blank area, the blank area being disposed around the patterned area, the patterned area including a main patterned area and a marking area disposed around the main patterned area; An blocking layer is formed on the surface of the blank area, the blocking layer is disposed around the marked area, the light transmittance of the blocking layer is 0%, and the light reflectance is 100%.
7. The forming method as described in claim 6, characterized in that, The method further includes: bonding a frame to the surface of the blocking layer with an adhesive layer, wherein the width of the frame is less than or equal to the width of the blocking layer, and the adhesive layer is used to bond the frame to the blocking layer.
8. The forming method as described in claim 6, characterized in that, The blocking layer material is metallic chromium.
9. The forming method as described in claim 6, characterized in that, The method for forming the blocking layer includes physical sputtering.
10. The forming method as described in claim 6, characterized in that, The width of the blocking layer is 2mm to 3mm, and the thickness of the blocking layer is 40nm to 50nm.