Photoetching method, mask and preparation method thereof
By designing the mask plate in the vertical area and optimizing the exposure process, the problem of inconsistent thermal expansion of the two-in-one mask plate is solved, high-quality lithography and high-precision overprinting are achieved, and cost is reduced.
Patent Information
- Application Number
- CN202510890606.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-28
- Publication Date
- 2025-08-15
AI Technical Summary
After the exposure time of the two-in-one mask plate doubles, the thermal expansion shape is inconsistent, resulting in the lithography machine being unable to fully compensate, affecting the graphics quality and engraving accuracy.
A mask plate is designed, including a first area and a second area that are perpendicular to each other, drawing the first and second figures respectively, and through the exposure process of a specific light source angle, the thermal effect is avoided in different areas, and the thermal effect is reduced by using the compensation method of the lithography machine.
It reduces the thermal effect of the mask plate, improves the quality of lithography graphics and intercalation accuracy, saves the cost of the mask plate, and improves product yield.
Smart Images
Figure CN120491384A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of integrated circuits, and in particular to a photolithography method, a mask and a preparation method thereof. Background Art
[0002] During the photolithography exposure process, repeated exposures of the mask cause thermal expansion, impacting wafer pattern quality and overlay accuracy. Typically, the imaging system of the lithography machine compensates for this, but only for reticles with uniform thermal expansion directions—that is, single-layer reticles. However, in actual R&D and production, to save reticle costs, two-in-one reticles are considered, doubling the exposure time. This leads to significant reticle thermal effects, and since the thermal expansion shapes vary, the machine cannot fully compensate, affecting pattern quality and overlay accuracy. Summary of the Invention
[0003] The purpose of the present invention is to provide a photolithography method, a mask and a preparation method thereof, so as to solve the problem that a two-in-one mask doubles the exposure time, resulting in serious mask thermal effect, and the machine cannot fully compensate for the different thermal expansion shapes, affecting the graphic quality and overlay accuracy.
[0004] To solve the above technical problems, the present invention provides a mask, which includes a first area and a second area, the first area and the second area are perpendicular to each other, the first area has a first pattern, and the second area has a second pattern.
[0005] Based on the same inventive concept, the present invention further provides a photolithography method, comprising:
[0006] Providing a mask, the mask comprising a first area and a second area, the first area and the second area being perpendicular to each other, the first area having a first pattern, and the second area having a second pattern;
[0007] Performing a first exposure process, with a signal light source perpendicular to the first area and a signal receiving plane parallel to the first area;
[0008] A second exposure process is performed, wherein the signal light source is perpendicular to the second area, and the signal receiving plane is parallel to the second area.
[0009] Optionally, after performing the first exposure process, a first development process is performed to transfer the first pattern of the mask to the signal receiving plane.
[0010] Optionally, after performing the second exposure process, a second development process is performed to transfer the second pattern of the mask to the signal receiving plane.
[0011] Optionally, before performing the second exposure process, the mask is rotated so that the second area is parallel to the signal receiving plane.
[0012] Optionally, the signal receiving plane is a wafer, and the wafer is located below the mask.
[0013] Optionally, when performing the first exposure process, the signal light source is parallel to the second area, and when performing the second exposure process, the signal light source is parallel to the first area.
[0014] Based on the same inventive concept, the present invention also provides a method for preparing a mask, comprising:
[0015] Providing a substrate, wherein the surface of the substrate is flat;
[0016] preparing a first region and a second region on the substrate, wherein the first region and the second region are perpendicular to each other;
[0017] A first graphic is drawn in the first area, and a second graphic is drawn in the second area.
[0018] Optionally, the steps of preparing the first region and the second region include:
[0019] The substrate is first etched using a physical etching process, and then treated using a chemical treatment process to form a first cut surface and a second cut surface on the substrate, wherein the first cut surface and the second cut surface are perpendicular to each other, the first cut surface constitutes a first region, and the second cut surface constitutes a second region.
[0020] Optionally, a laser or an electron beam is used to draw a first pattern in the first area, and a second pattern is drawn in the second area.
[0021] In the mask provided by the present invention, the mask includes a first area and a second area, the first area and the second area are perpendicular to each other, the first area has a first pattern, and the second area has a second pattern. Since the first area and the second area of the mask are perpendicular to each other, when exposing the first pattern, the signal light source is parallel to the second pattern, and no thermal effect is generated on the second pattern. When exposing the second pattern, the signal light source is parallel to the first pattern, and no thermal effect is generated on the first pattern, thereby reducing the thermal effect of the mask, and the lithography machine can compensate for the thermal effect of the mask in a normal compensation manner. The mask provided by the present invention retains the advantages of a two-in-one mask, saves the cost of the mask, and at the same time reduces the thermal effect of the mask, and the lithography machine can compensate for the thermal effect of the mask, thereby improving the quality of the lithography pattern and the overlay accuracy, and improving the product yield. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.
[0023] Figure 1 It is a schematic structural diagram of a mask according to an embodiment of the present invention.
[0024] Figure 2 4 is a flow chart of a photolithography method according to an embodiment of the present invention.
[0025] Figure 3 This is a diagram showing the relative positions of a signal light source, a mask, and a signal receiving plane in a photolithography process according to an embodiment of the present invention.
[0026] Figure 4 It is a flow chart of a method for preparing a mask according to an embodiment of the present invention.
[0027] Figure 5-Figure 6 It is a structural schematic diagram corresponding to the steps of a method for preparing a mask according to an embodiment of the present invention.
[0028] In the attached figure:
[0029] 20-signal receiving plane; 10-mask; 11-substrate; 11a-first area; 11b-second area; 12a-first graphic; 12b-second graphic;. DETAILED DESCRIPTION
[0030] To make the objects, advantages, and features of the present invention more clearly apparent, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale. They are only used to conveniently and clearly assist in illustrating the purposes of the embodiments of the present invention. In addition, the structures shown in the drawings are often part of the actual structure. In particular, different drawings may need to illustrate different focuses and sometimes use different scales.
[0031] As used in the present invention, the singular forms "a", "an", and "the" include plural objects, the term "or" is generally used to include the meaning of "and / or", the term "several" is generally used to include the meaning of "at least one", and the term "at least two" is generally used to include the meaning of "two or more". In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features specified as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features. In addition, as used in the present invention, an element is provided on another element, which generally only indicates that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the connection, coupling, cooperation or transmission between the two elements can be direct or indirect through an intermediate element, and should not be understood to indicate or imply the spatial position relationship between the two elements, that is, one element can be in any orientation such as inside, outside, above, below, or to the side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0032] Figure 1 FIG is a schematic structural diagram of a mask according to an embodiment of the present invention. Figure 1 As shown, this embodiment provides a mask 10, comprising a first region 11a and a second region 11b. The first region 11a and the second region 11b are perpendicular to each other, i.e., the angle θ between the first region 11a and the second region 11b is 90°. The first region 11a has a first pattern 12a, and the second region 11b has a second pattern 12b. Because the first and second regions of the mask are perpendicular to each other, when exposing the first pattern, the signal light source is parallel to the second pattern, resulting in no thermal effect on the second pattern. When exposing the second pattern, the signal light source is parallel to the first pattern, resulting in no thermal effect on the first pattern. This reduces the thermal effect on the mask, allowing the lithography machine to compensate for the thermal effect of the mask using normal compensation methods. The mask provided by the present invention retains the advantages of a two-in-one mask, saves mask costs, and reduces the thermal effect of the mask. The lithography machine can compensate for the thermal effect of the mask, thereby improving the quality of the lithography pattern and overlay accuracy, thereby increasing product yield.
[0033] Figure 2 FIG. 1 is a flow chart of a photolithography method according to an embodiment of the present invention. Figure 2 As shown, this embodiment further provides a photolithography method, including:
[0034] Step S11, providing a mask, wherein the mask includes a first region and a second region, the first region and the second region are perpendicular to each other, the first region has a first pattern, and the second region has a second pattern;
[0035] Step S12, performing a first exposure process, with the signal light source being perpendicular to the first area and the signal receiving plane being parallel to the first area;
[0036] Step S13 , performing a second exposure process, wherein the signal light source is perpendicular to the second area, and the signal receiving plane is parallel to the second area.
[0037] Figure 3 FIG is a diagram showing the relative position relationship between the signal light source, the mask, and the signal receiving plane in the photolithography process according to an embodiment of the present invention. Figure 1 and Figure 3 As shown, a mask 10 is provided, which includes a first area 11a and a second area 11b. The first area 11a and the second area 11b are perpendicular to each other. The first area 11a has a first pattern 12a, and the second area 11b has a second pattern 12b.
[0038] A substrate is provided. In some embodiments, the substrate can be a semiconductor substrate made of any semiconductor material suitable for semiconductor devices (such as Si, SiC, SiGe, etc.). In other embodiments, the substrate can also be various composite substrates such as silicon-on-insulator (SOI) and silicon-germanium-on-insulator (SiGe-on-insulator). Those skilled in the art will appreciate that the substrate is not subject to any limitation and can be selected based on the actual application. Various device components (not limited to semiconductor devices) can be formed in the substrate (not shown in the figure). The substrate can also have other layers or components formed thereon, such as gate structures, contact holes, dielectric layers, metal connections, and vias. The substrate is located on the signal receiving plane 20. The substrate is located below the mask 10. In this embodiment, the substrate is, for example, a wafer, i.e., the wafer is located below the mask 10. A hard mask layer, an anti-reflective layer, and a first photoresist layer are formed on the substrate. Other semiconductor devices and dielectric layers can also be formed between the substrate and the hard mask layer, although this embodiment does not limit this.
[0039] During a first exposure process, the signal light source of the exposure device is perpendicular to the first region 11a, and the signal receiving plane 20 is parallel to the first region 11a. The signal light source illuminates the first region 11a perpendicularly and transmits a portion of the light beam to illuminate the first photoresist layer of the substrate. During the first exposure process, the signal light source is parallel to the second region 11b. Therefore, during the first exposure process, only the first region 11a experiences a thermal effect; the second region 11b is not illuminated by the signal light source and, therefore, does not experience a thermal effect.
[0040] After the first exposure process, a first development process is performed to transfer the first pattern 12a of the mask to the signal receiving plane 20, that is, to transfer the first pattern 12a of the mask to the first photoresist layer of the substrate, forming a patterned first photoresist layer. In a subsequent etching process, the hard mask layer and substrate are further etched using the patterned first photoresist layer as a mask to transfer the first pattern 12a to the substrate. After the step of forming the first pattern 12a, if the patterned first photoresist layer has not been completely consumed, a photoresist removal process is required, typically using an ashing process or stripping to remove the remaining patterned first photoresist layer.
[0041] Before performing the second exposure process, the mask 10 is rotated so that the second region 11 b is parallel to the signal receiving plane 20. A second photoresist layer is formed on the substrate.
[0042] During the second exposure process, the signal light source is perpendicular to the second region 11b, and the signal receiving plane 20 is parallel to the second region 11b. The signal light source shines perpendicularly on the second region 11b and transmits a portion of the light beam to illuminate the second photoresist layer of the substrate. During the second exposure process, the signal light source is parallel to the first region 11a. Therefore, during the second exposure process, only the second region 11b experiences a thermal effect; the first region 11a is not illuminated by the signal light source, and therefore, no thermal effect occurs in the first region 11a.
[0043] After the second exposure process, a second development process is performed to transfer the second pattern 12b of the mask to the signal receiving plane 20. Specifically, the second pattern 12b of the mask is transferred to the second photoresist layer on the substrate, forming a patterned second photoresist layer. In a subsequent etching process, the hard mask layer and substrate are further etched using the patterned second photoresist layer as a mask to transfer the second pattern 12b to the substrate. After forming the second pattern 12b, if the patterned second photoresist layer has not been completely consumed, a photoresist removal process is required. This is typically performed by ashing or stripping to remove the remaining patterned second photoresist layer. Because the first region 11a and the second region 11b of the mask in this embodiment are perpendicular to each other, when exposing the first pattern 12a, the signal light source is parallel to the second pattern 12b, resulting in no thermal effect on the second pattern 12b. When exposing the second pattern 12b, the signal light source is parallel to the first pattern 12a, resulting in no thermal effect on the first pattern 12a, thereby reducing the thermal effect on the mask. Because the first region 11a and the second region 11b of the mask are perpendicular to each other, the lithography machine can compensate for the thermal effects of the mask using normal compensation methods. The reticle provided in this embodiment retains the advantages of a two-in-one mask, saving mask costs while reducing the thermal effects of the mask. Furthermore, the lithography machine can compensate for the thermal effects of the mask, thereby improving the quality of the lithography pattern and overlay accuracy, and increasing product yield.
[0044] Figure 4 FIG. 1 is a flow chart of a method for preparing a mask according to an embodiment of the present invention. Figure 4 As shown, this embodiment also provides a method for preparing a mask, including:
[0045] Step S21, providing a substrate, wherein the surface of the substrate is flat;
[0046] Step S22, preparing a first region and a second region on the substrate, wherein the first region and the second region are perpendicular to each other;
[0047] Step S23: draw a first graphic in the first area, and draw a second graphic in the second area.
[0048] Figure 5-Figure 6 This is a schematic structural diagram corresponding to the steps of the method for preparing a mask according to an embodiment of the present invention. Figures 5 and 6 The preparation process of the mask is introduced in detail.
[0049] like Figure 5 As shown, a substrate 11 is provided, and the surface of the substrate 11 is flat. The substrate 11 is usually made of synthetic quartz glass or borosilicate glass with high purity, low defects and low thermal expansion coefficient.
[0050] like Figure 6As shown, a physical etching process is first used to etch the substrate 11, and then a chemical treatment process is used to treat the substrate 11 to form a first cut surface and a second cut surface on the substrate 11. The angle θ between the first cut surface and the second cut surface is 90°, that is, the first cut surface and the second cut surface are perpendicular to each other. The first cut surface constitutes a first region 11a, and the second cut surface constitutes a second region 11b. A very thin light-shielding layer is usually deposited on the surface of the first region 11a and the second region 11b as a basis. The light-shielding material of the light-shielding layer is, for example, a chromium layer or MoSi (molybdenum silicide). Preferably, an adhesion-enhancing layer is first deposited on the surface of the first region 11a and the second region 11b to improve the adhesion of the subsequent light-shielding layer to the substrate. The adhesion-enhancing layer is, for example, a compound such as chromium or silicon.
[0051] like Figure 1 As shown, a laser or electron beam is used to draw a first pattern 12a in the first area 11a, and a second pattern 12b in the second area 11b. Specifically, a uniform, ultra-thin layer of photoresist is spin-coated on the light-shielding layer of the first area 11a and the second area 11b. The photoresist used for mask production is usually electron beam photoresist because it requires extremely high resolution, which is much higher than silicon wafer lithography. A laser direct writing device or an electron beam lithography machine is used to draw the designed integrated circuit layout directly onto the photoresist. The exposed substrate is immersed in a specific developer to dissolve the photoresist in the exposed (or unexposed, depending on the type of photoresist) area, thereby forming the desired hollow pattern on the photoresist layer.
[0052] From the above, it can be seen that in the mask provided in the embodiment of the present invention, the mask includes a first area and a second area, the first area and the second area are perpendicular to each other, the first area has a first pattern, and the second area has a second pattern. Since the first area and the second area of the mask are perpendicular to each other, when exposing the first pattern, the signal light source is parallel to the second pattern, and no thermal effect is generated on the second pattern. When exposing the second pattern, the signal light source is parallel to the first pattern, and no thermal effect is generated on the first pattern, thereby reducing the thermal effect of the mask, and the lithography machine can compensate for the thermal effect of the mask in a normal compensation manner. The mask provided by the present invention retains the advantages of a two-in-one mask, saves the cost of the mask, and at the same time reduces the thermal effect of the mask, and the lithography machine can compensate for the thermal effect of the mask, thereby improving the quality of the lithography pattern and the overlay accuracy, and improving the product yield.
[0053] Furthermore, it should be recognized that although the present invention has been disclosed above with reference to preferred embodiments, the above embodiments are not intended to limit the present invention. Any person skilled in the art can utilize the above disclosed technical content to make many possible changes and modifications to the technical solution of the present invention, or modify it into equivalent embodiments with equivalent variations, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent variations, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.
Claims
1. A mask, characterized in that: The mask includes a first area and a second area, the first area and the second area are perpendicular to each other, the first area has a first pattern, and the second area has a second pattern.
2. A photolithography method, characterized in that: include: Providing a mask, the mask comprising a first area and a second area, the first area and the second area being perpendicular to each other, the first area having a first pattern, and the second area having a second pattern; Performing a first exposure process, with a signal light source perpendicular to the first area and a signal receiving plane parallel to the first area; A second exposure process is performed, wherein the signal light source is perpendicular to the second area, and the signal receiving plane is parallel to the second area.
3. The photolithography method according to claim 2, wherein: After performing the first exposure process, a first development process is performed to transfer the first pattern of the mask onto the signal receiving plane.
4. The photolithography method according to claim 2, wherein: After performing the second exposure process, a second development process is performed to transfer the second pattern of the mask onto the signal receiving plane.
5. The photolithography method according to claim 2, wherein: Before performing the second exposure process, the mask is rotated so that the second region is parallel to the signal receiving plane.
6. The photolithography method according to any one of claims 2 to 5, characterized in that: The signal receiving plane is a wafer, and the wafer is located below the mask.
7. The photolithography method according to claim 2, wherein: When the first exposure process is performed, the signal light source is parallel to the second region. When the second exposure process is performed, the signal light source is parallel to the first region.
8. A method for preparing a mask, characterized in that: include: Providing a substrate, wherein the surface of the substrate is flat; preparing a first region and a second region on the substrate, wherein the first region and the second region are perpendicular to each other; A first graphic is drawn in the first area, and a second graphic is drawn in the second area.
9. The method for preparing a mask according to claim 8, wherein: The steps of preparing the first region and the second region include: The substrate is first etched using a physical etching process, and then treated using a chemical treatment process to form a first cut surface and a second cut surface on the substrate, wherein the first cut surface and the second cut surface are perpendicular to each other, the first cut surface constitutes a first region, and the second cut surface constitutes a second region.
10. The method for preparing a mask according to claim 8, wherein: A first pattern is drawn in the first region by using a laser or an electron beam, and a second pattern is drawn in the second region.