Method for patterning a side surface of a substrate and semiconductor device

Abstract

The application provides a method for patterning a side surface of a substrate and a semiconductor device, and belongs to the field of photolithography. The method comprises the following steps: providing a substrate, the substrate being provided with a side wall; preparing a pattern transfer medium on the substrate to form a photoresist layer covering the side wall; for a target exposure area on the side wall covered with the photoresist layer, performing first oblique exposure according to preset initial exposure parameters to form a first actual exposure area; based on the first actual exposure area and the target exposure area, correcting the initial exposure parameters to determine corrected exposure parameters; performing second oblique exposure according to the corrected exposure parameters, so that a second actual exposure area obtained by the second oblique exposure is consistent with the target exposure area; and performing a metal patterning operation to form a metal pattern in the second actual exposure area. The application realizes high-fidelity side wall patterning and improves the accuracy of the pattern position.

Description

Technical Field

[0001] This application relates to the field of photolithography technology, and more particularly to a method for patterning the side metal of a substrate and a semiconductor device. Background Technology

[0002] In the rapid development of semiconductor technology towards 3D integration, microelectromechanical systems (MEMS), and high-density packaging, achieving precise metal patterning on the vertical sidewalls of deep trench / high aspect ratio structures has become a crucial core process. This technology is fundamental to building high-performance 3D transistors, high-density through-silicon via (TSV) interconnects, large-capacity deep trench capacitors, high-sensitivity MEMS sensors, and advanced radio frequency devices.

[0003] Traditional optical lithography is a planar projection imaging system. Its physical principles dictate that it can only form clear patterns on a horizontal focal plane. For vertical sidewalls, effective exposure is impossible due to limitations in light and optical path. Existing technologies utilize the significant difference between the directionality of isotropic and anisotropic etching in conformal deposition to conformally and uniformly cover all materials across the entire three-dimensional structure. Then, through top-down, highly anisotropic etching, material in specific areas is selectively removed, ultimately obtaining the pattern on the sidewalls. Alternatively, by modifying the exposure system (tilted incidence, multi-angle), three-dimensional structures with tilted sidewalls can be directly formed in the photoresist layer to achieve vertical sidewall patterning. However, these methods have significant limitations. The former involves complex processes, high implementation costs, and extremely low design freedom, while the latter relies on experience to adjust parameters such as exposure angle and dosage, requiring multiple trials to obtain a qualified pattern, resulting in long development cycles and high costs.

[0004] Therefore, it is particularly important to propose a method for metal patterning the side of the substrate trench. Summary of the Invention

[0005] Based on this, the purpose of this application is to provide a method for patterning the side metal of a substrate and a semiconductor device to solve at least one of the above-mentioned technical problems.

[0006] In a first aspect, this application provides a method for patterning the side metal of a substrate, the method comprising: Step 1, providing a substrate, wherein the substrate has sidewalls; Step 2: Prepare a pattern transfer medium on the substrate to form a photoresist layer covering the sidewalls; Step 3: For the target exposure area covered by photoresist layer on the sidewall, the first exposure is performed using a tilted exposure method according to the preset initial exposure parameters to form the first actual exposure area; Step 4: Based on the first actual exposure area and the target exposure area, correct the initial exposure parameters and determine the corrected exposure parameters; Step 5: Perform a second tilt exposure according to the corrected exposure parameters, so that the second actual exposure area obtained by the second tilt exposure is consistent with the target exposure area; Step 6: Perform a metal patterning operation to form a metal pattern in the second actual exposure area.

[0007] Optionally, the initial exposure parameters include the initial tilt angle and the initial coordinates of the marker points on the photomask; The first exposure, performed using a tilted exposure method according to preset initial exposure parameters, to form a first actual exposure area, includes: The photomask is placed on top of the substrate at a preset position, so that the marked points are at the corresponding initial coordinates, and the target exposure area is exposed according to the initial tilt angle. Determine the distance between the end of the first actual exposure area and the end of the corresponding sidewall.

[0008] Optionally, determining the corrected exposure parameters based on the first actual exposure area and the target exposure area includes: The exposure deviation area is determined based on the first actual exposure area and the target exposure area; Keeping the initial tilt angle unchanged, the corrected coordinates of the marker point are determined based on the exposure deviation area and the initial tilt angle. The corrected exposure parameters include the corrected coordinates and the initial tilt angle.

[0009] Optionally, determining the corrected exposure parameters based on the first actual exposure area and the target exposure area includes: The exposure deviation area is determined based on the first actual exposure area and the target exposure area; Keeping the initial coordinates of the marked point unchanged, a corrected tilt angle is determined based on the exposure deviation area and the initial coordinates. The corrected exposure parameters include the initial coordinates and the corrected tilt angle.

[0010] Optionally, determining the exposure deviation region based on the first actual exposure region and the target exposure region includes: calculating the deviation distance between the edge position of the first actual exposure region and the edge position of the target exposure region. ; The step of determining the corrected coordinates of the marker point based on the exposure deviation area and the initial tilt angle includes: according to the formula Calculate the distance to be corrected for the marker points along the horizontal arrangement direction of multiple sidewalls. Based on the distance to be corrected The corrected coordinates of the marker point are determined from the initial coordinates.

[0011] Optionally, determining the exposure deviation region based on the first actual exposure region and the target exposure region includes: calculating the deviation distance between the edge position of the first actual exposure region and the edge position of the target exposure region. ; The step of determining the corrected tilt angle based on the exposure deviation area and the initial coordinates includes: based on trigonometric relationships, according to the deviation distance... Initial tilt angle The positional relationship between the marked points and the corresponding sidewalls under the initial coordinates is used to calculate the corrected tilt angle.

[0012] Optionally, the initial tilt angle may include multiple angles, or the initial tilt angle may be a variable angle; The exposure processing of the target exposure area according to the initial tilt angle includes: exposing the target exposure area according to different initial tilt angles, such that the initial tilt angle used to form the lower edge of the first actual exposure area is greater than the initial tilt angle used to form the upper edge of the first actual exposure area.

[0013] Optionally, the initial tilt angle includes an initial first tilt angle and an initial second tilt angle; The exposure processing of the target exposure area according to the initial tilt angle includes: exposing a first sub-region of the first actual exposure area according to the initial first tilt angle, and controlling the tilt exposure device to expose a second sub-region of the first actual exposure area according to the initial second tilt angle, wherein the first sub-region is below the second sub-region, and the first tilt angle is greater than the second tilt angle.

[0014] Optionally, the metal patterning operation, which forms a metal pattern in the second actual exposure area, includes: Step 61: Develop the second actual exposure area to form a sidewall metal window pattern; Step 62: Sputter metal onto the developed substrate to form the target metal layer; Step 63: The substrate after sputtering metal is stripped to form a metal pattern.

[0015] Optionally, an etching process is used to create grooves in the substrate to form multiple grooves including sidewalls; In step 2, the substrate after grooving is subjected to an adhesive enhancement treatment. The pattern transfer medium is covered to the sidewall by ultrasonic atomization spraying. The pattern transfer medium is positive photoresist. In step 61, the substrate after the second exposure is immersed and developed using a positive photoresist developer, and the immersed substrate is dried using nitrogen gas. In step 62, Ti or Au metal is selected, and magnetron sputtering is used to sputter the developed substrate. In step 63, NMP is selected as the stripping agent, and an ultrasonic-assisted immersion process is used to strip the substrate after sputtering metal.

[0016] In a second aspect, this application provides a semiconductor device that performs the methods described in any embodiment of this application.

[0017] In a third aspect, this application provides an electronic device including the semiconductor device described in the second aspect.

[0018] This application discloses a method for metallizing the side of a substrate and a semiconductor device. The method involves a series of processes: coating, exposure, development, and metallizing the side of the substrate. Multiple tilted exposures are performed on the side of the substrate. Based on the deviation between the first actual exposure area and the target exposure area formed by the first exposure, corrected exposure parameters are calculated for the second exposure. The substrate is then re-exposed according to these corrected parameters, resulting in a better match between the second actual exposure area and the target exposure area. This achieves high-fidelity sidewall patterning, improves the accuracy of the pattern position, simplifies the process, and reduces costs. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0020] Figure 1 This is a schematic diagram of the process of a method for patterning the side metal of a substrate in one embodiment; Figure 2 This is a flowchart illustrating a method for patterning the side metal of a substrate in one embodiment. Figure 3 This is a schematic diagram illustrating the positional relationship between the photomask and the substrate in one embodiment. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] All terms used in this application (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0023] For example, the terms "first," "second," etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For instance, without departing from the scope of this application, a first analytical result may be referred to as a second analytical result, and similarly, a second analytical result may be referred to as a first analytical result. Both the first analytical result and the second analytical result are analytical results, but they are not the same analytical result.

[0024] For example, the terms "comprising" or "including" used in this application indicate the presence of features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0025] In one embodiment, a method for patterning the side metal of a substrate is provided, combined with Figure 1 and Figure 2 As shown, the method includes the following steps: Step 1, providing a substrate, the substrate having sidewalls.

[0026] In this embodiment, the substrate serves as the platform and functional material body for all subsequent micro / nano fabrication. It can be the base wafer used as a processing carrier in semiconductor processes, such as a P-type single-crystal silicon wafer, gallium arsenide wafer, or silicon carbide wafer. The sidewalls are vertical surfaces extending along the height direction on the substrate. They can be perpendicular to the substrate surface or at a certain angle. The specific shape of the sidewalls can be any suitable shape, such as stepped sidewalls, boss sidewalls, microstructure sidewalls, or isolation pillar sidewalls.

[0027] In one embodiment, the sidewalls may be sidewalls on a substrate trench. A trench is a recessed structure formed by etching on a substrate, having sidewalls and a bottom. The trench has a certain depth and width, and the sidewalls of the trench are typically 90° or close to 90°. Multiple trenches may be provided on the substrate, and these trenches may be uniformly or non-uniformly distributed in the same direction. The size and / or shape of each trench may be the same or different. For example, the depth and width of the trench can both be within any suitable range such as 20μm to 500μm, and its depth-to-width ratio can be 10:1 to 1:1. Optionally, the trench width can be 20μm, 50μm, 100μm, etc., and the trench depth can be 50μm, 100μm, 200μm, 300μm. Among them, the groove width refers to the distance between the two side walls of the groove, which can also be understood as the lateral interval between a single side wall and the incident direction of the exposure light; this width determines whether the tilted exposure light can successfully reach the target area of ​​the side wall; the groove depth refers to the vertical distance from the bottom of the groove to the upper surface of the substrate. The greater the depth, the more obvious the projection offset of the tilted exposure.

[0028] There are various methods for creating substrate trenches, such as wet etching, dry etching, ion etching, and any suitable combination of one or more methods to create one or more trenches. In one embodiment, an etching process can be used to create trenches, such as the Bosch process of deep reactive ion etching (DRIE) to create trenches on the substrate, forming multiple trenches. Among them, the Bosch process of deep reactive ion etching (DRIE) is a dominant dry etching technology for etching deep trenches or deep holes with high aspect ratios, vertical sidewalls, and controllable depth on silicon. Its core principle is a rapid alternating cycle of passivation and etching. A standard Bosch cycle includes a passivation step and an etching step. In the passivation step, a fluorine-containing gas such as octafluorocyclobutane (C4F8) is introduced, and under plasma, a thin Teflon-like polymer film is deposited throughout the etched area (bottom and sidewalls). The etching step is switched to sulfur hexafluoride (SF6) gas. The fluorine radicals generated by the SF6 plasma isotropically etch silicon. However, due to the physical direction of ion bombardment being vertically downwards, ion bombardment at the bottom of the trench can penetrate and remove the passivation layer, allowing the fluorine radicals to contact and etch the silicon at the bottom. On the trench sidewalls, however, ions are grazing parallel to the surface and cannot effectively remove the passivation layer, thus protecting the silicon on the sidewalls from etching. The passivation and etching steps are performed alternately at an extremely high frequency (typically several to tens of cycles per second) to achieve vertically downward etching of silicon. The trenches are then created using Bosch's Deep Reactive Ion Etching (DRIE) process, resulting in a very high aspect ratio (e.g., depth). Width only (100:1 aspect ratio) and nearly vertical sidewalls (achievable with Bosch process) (side wall angle).

[0029] Step 2: Prepare a pattern transfer medium on the substrate to form a photoresist layer covering the sidewalls.

[0030] In this embodiment, the pattern transfer medium is a photosensitive material, such as photoresist, used to transfer the exposed pattern onto the substrate. The photoresist layer is a uniform photosensitive film that, in addition to covering the sidewalls, can simultaneously cover other areas of the substrate, such as the bottom of the trench. The pattern transfer medium is prepared by ultrasonic atomization, pressure spraying, electrostatic spraying, or other methods. Any suitable process, such as spin coating, spraying, or roll coating, can be used for photoresist spraying to form a uniformly thick photoresist layer on the entire substrate (including the sidewalls of the trench).

[0031] For example, an ultrasonic atomization spraying method can be used to form a photoresist layer, and the photoresist used can be either positive or negative. Specifically, the substrate after trenching undergoes an adhesion-enhancing treatment. The hydrophobic surface formed by the adhesion-enhancing treatment has excellent chemical compatibility and affinity with the photoresist, forming a strong chemical bond. This prevents the photoresist from wrinkling, peeling off, or drilling during subsequent wet processes (development, etching, and stripping), and avoids the evaporation of moisture adsorbed on the substrate during subsequent baking, which could lead to bubbles or pinholes within the photoresist film. The substrate is then sprayed with photoresist using an ultrasonic atomization spraying method to form a photoresist layer covering the bottom and sidewalls of the trench. This photoresist layer can have any suitable thickness, such as 3–5 μm.

[0032] The ultrasonic atomization photoresist spraying method utilizes ultrasound to atomize liquid photoresist into uniform aerosol particles of micron-sized dimensions. These atomized particles are then transported and deposited onto the substrate surface by a carrier gas (such as nitrogen). This allows for precise control of the spraying area and flow rate, resulting in a highly uniform film thickness. When the sprayed photoresist is positive, the exposed areas are dissolved and removed during development. After development, the unexposed areas are retained, resulting in a robust photoresist structure that effectively supports the metal film on top. This leads to clean pattern edges during stripping, better tolerance for insufficient exposure (e.g., at the bottom of sidewalls), avoids accidental pattern breakage, and increases reliability, meeting requirements for high sidewall coverage, low surface tension, and good deep trench filling. Conversely, when the sprayed photoresist is negative, the unexposed areas are removed after development, while the exposed areas are retained.

[0033] By spraying photoresist onto the substrate, a uniform, consistent, and firmly bonded photoresist film is formed on the entire inner surface of a deep trench with a high aspect ratio and vertical sidewalls. This ensures that the photoresist at any depth on the sidewalls has consistent physicochemical properties, laying the foundation for subsequent tilt exposure and development.

[0034] Step 3: For the target exposure area covered by the photoresist layer on the sidewall, the first exposure is performed using the tilt exposure method according to the preset initial exposure parameters to form the first actual exposure area.

[0035] In this embodiment, the target exposure area refers to the area pre-planned at a specific location on the sidewall during the chip design phase, with a specific shape and size, which needs to be exposed and ultimately form a metal pattern. The target exposure area can be set in any suitable region of the entire sidewall, such as the middle, upper, or lower section, for example, a specific local area in the middle of the sidewall. For instance, if the trench width is 50 μm and the trench depth is 220 μm, the target exposure area is located in a region 100 μm to 200 μm high on the sidewall.

[0036] The initial exposure of the eye-viewing area is performed using a tilted exposure method according to preset initial exposure parameters. This tilted exposure method can be achieved in two ways: one is to tilt the substrate sample containing deep grooves, changing the target sidewalls from a vertical to a tilted state, so that they are approximately perpendicular to the direction of the incident light; the other is to deflect the light beam itself at a certain angle, illuminating the horizontally placed substrate sample at a tilted angle. For example, the light source can be incident at any suitable tilt angle relative to the plane of the substrate, such as 15°, 30°, 45°, or 60°.

[0037] like Figure 1 As shown, EUV (Extraviolet Light) can be used as the exposure light source. The preset initial exposure parameters are ideal state parameters derived from physical laws and theoretical models, including the initial tilt angle and the initial coordinates of the marker points on the photomask. The initial tilt angle is the incident tilt angle of the light source (or incident light) relative to the vertical direction (or the direction of the substrate normal or the direction of the trench sidewall). The marker points on the photomask are used to identify the precise position and rotation angle of the plate in the lithography machine. When the marker points on the photomask are at their corresponding initial coordinates, it indicates that the photomask has been placed in the corresponding initial placement position (preset position). Its initial coordinates at the initial placement position reflect the relative alignment between the photomask and the substrate. The photomask has corresponding slits / holes located directly above / slanted above the groove of the substrate. The light source can shine through these slits / holes onto the sidewall of the groove, thereby exposing the first actual exposure area of ​​the sidewall.

[0038] Specifically, for the target exposure area of ​​the sidewall of the substrate with a photoresist layer, a tilted exposure method is used to perform the first exposure and development according to the preset initial exposure parameters, and the first actual exposure area formed after the first development is determined.

[0039] The development method can be any suitable method such as immersion development, spray development, or mist development. After the first development, the first actual exposure area is formed. For positive photoresist, the photoresist in the exposed area undergoes a chemical reaction and is dissolved in the developer, thereby physically forming a window on the photoresist layer. At this time, a real and visible physical pattern appears on the sidewall, which is the entity of the first actual exposure area.

[0040] Step 4: Based on the first actual exposure area and the target exposure area, correct the initial exposure parameters to determine the corrected exposure parameters.

[0041] In this embodiment, the corrected exposure parameters are used for reverse compensation and to offset the systematic errors exposed in the first exposure, thereby reducing the error between the ideal parameters and the actual parameters. The output parameter format is the same as the initial exposure parameters.

[0042] When the photomask is in the preset position, there is a certain gap between it and the top of the substrate. The height of this gap is difficult to measure accurately. Therefore, even when exposure is performed according to the theoretically calculated initial exposure parameters, the resulting first actual exposure area still deviates from the target exposure area. The position of the first actual exposure area can be calculated. Based on this position and the target area position of the target exposure area, the positional deviation can be calculated. Then, combined with the initial exposure parameters used, corrected exposure parameters for the second exposure can be calculated. This ensures that when exposure is performed based on these corrected exposure parameters, the resulting exposure area matches the target exposure area more closely, or the positional deviation is smaller.

[0043] Step 5: Perform a second tilt exposure according to the corrected exposure parameters, so that the second actual exposure area obtained by the second tilt exposure is consistent with the target exposure area.

[0044] In this embodiment, the photoresist on the substrate is removed and re-sprayed, and a second tilt exposure is performed according to the calculated corrected exposure parameters, so that the second actual exposure area obtained by the second tilt exposure is consistent with the target exposure area.

[0045] Before performing the second tilt exposure, the photoresist on the substrate needs to be removed and re-sprayed. The chemical properties of the photoresist have changed after the first exposure, and continued use will lead to inaccurate results in subsequent exposures.

[0046] Specifically, apart from the difference in exposure parameters, the exposure methods can remain unchanged between the two exposures. The photoresist removal process can be the same as the removal process described below, and the re-spraying process can be the same as the spraying process in step 2.

[0047] After the first exposure, the photoresist is ultrasonically cleaned with deionized water. The ultrasonic power is controlled at 30-50W and the cleaning time is 10-15 seconds. After cleaning, it is dried with nitrogen to avoid residual impurities affecting the effect of secondary coating and to ensure that the coating layer is uniform and flawless after the second coating.

[0048] Next, a second tilt exposure is performed based on the corrected exposure parameters calculated in step 4. This ensures that the equipment conditions (temperature, humidity, vibration) during the second exposure are consistent with those during the first exposure, avoiding the introduction of new errors and ensuring that the second actual exposure area obtained from the second tilt exposure matches the target exposure area. Specifically, consistency is determined by whether there is misalignment, deformation, or image clarity between the second actual exposure area and the target exposure area.

[0049] Step 6: Perform a metal patterning operation to form a metal pattern in the second actual exposure area.

[0050] The patterning operation may include development, metal deposition, and stripping operations to form a metal pattern in a predetermined area on the sidewall.

[0051] In one embodiment, step 6 includes: step 61, developing the second actual exposure area to form a sidewall metal window pattern; step 62, sputtering metal onto the developed substrate to form a target metal layer; and step 63, stripping the sputtered metal substrate to form a metal pattern.

[0052] In this embodiment, the second actual exposure area in step 5 is transformed into a clear windowed pattern through development. After development, the removed area on the originally continuously covered photoresist layer forms one or more windowed patterns. The shape, size, and position of this window are the result of the exposure parameter correction in step 5. The sidewall metal windowed pattern refers to a window located on the vertical sidewall of the deep trench; its shape is the negative image of the metal pattern to be formed later (where the photoresist is removed, metal will appear after subsequent processing; where the photoresist remains, no metal will appear after subsequent processing). The first and second development processes can be the same.

[0053] For sputtering processes, magnetron sputtering or any other suitable method can be used to form the metal layer. Taking positive photoresist as an example, the substrate after the second development includes a windowed region (sidewall metal windowed pattern) and a non-windowed region (the area covered by photoresist excluding the sidewall metal windowed pattern). Due to the height difference between the photoresist and the substrate surface, the sputtered metal film will naturally break at the photoresist edge, forming two independent parts, providing a foundation for subsequent steps. The target metal layer refers to the metal layer that is ultimately left on the sidewall of the deep trench, i.e., the windowed region (sidewall metal windowed pattern) metal layer.

[0054] For the stripping process, any suitable method can be used, such as immersion stripping, ultrasonic-assisted stripping, or heat stripping. By stripping the substrate after sputtering metal, the non-windowed areas (the areas covered by photoresist except for the sidewall metal windowed patterns) in the substrate after the second development are removed, while the windowed areas (sidewall metal windowed patterns) are retained, thus forming a metal pattern.

[0055] In one embodiment, when multiple trenches with the same aspect ratio exist, an initial exposure can be performed on one or several of these trenches. Corrected exposure parameters are then calculated based on these initial exposures, and the remaining trenches with the same aspect ratio do not require an initial exposure; instead, the calculated corrected exposure parameters are used to achieve accurate exposure in a single step.

[0056] like Figure 1 As shown, firstly, the desired trench structure is pre-etched on the silicon substrate surface to prepare for subsequent photoresist filling and pattern transfer. Then, a layer of photoresist is uniformly coated on the entire substrate surface (including the inner walls of the trenches) as the photosensitive material for subsequent exposure and development. Next, extreme ultraviolet (EUV) light is used to selectively expose specific areas of the photoresist (usually the trench sidewalls or top edges) from an oblique angle or side. Due to the shading effect of the trench structure, only the photoresist exposed in the light path is activated (the blue arrow in the figure represents the incident light), thus achieving the patterning of the non-planar structure. Next, the exposed (or unexposed, depending on the type of photoresist) photoresist is removed, exposing the areas below that need to be etched or deposited with metal. Then, a metal film is deposited on the entire surface (including inside and outside the trenches) for subsequent formation of conductive lines. Finally, excess metal and residual photoresist are removed, leaving only the metal structure filled in the trenches to form the final metal interconnect pattern.

[0057] The method for metal patterning the side of a substrate in this application involves a series of processes, including coating, exposure, development, and metal patterning, on the side of the substrate. Multiple tilted exposures are applied to the side of the substrate. Due to the difficulty in accurately measuring the actual distance between the photomask and the substrate in the height direction, and / or the influence of light deviation, there will be a certain positional deviation between the first actual exposure area formed according to the initial exposure parameters and the target area. Based on this positional deviation and the initial exposure parameters, corrected exposure parameters can be calculated. Then, coating is resumed, and exposure is repeated according to the calculated corrected exposure parameters. This makes the second actual exposure area more closely match the target exposure area, improving the accuracy of the subsequent metal patterning position.

[0058] In one embodiment, the initial exposure parameters include an initial tilt angle and the initial coordinates of the marker points on the photomask. Step 3 involves performing a first exposure using a tilt exposure method according to the preset initial exposure parameters to form a first actual exposure area. This includes: placing the photomask above the substrate at a preset position, positioning the marker points at their corresponding initial coordinates, and exposing the target exposure area according to the initial tilt angle; determining the distance between the end of the first actual exposure area and the end of the corresponding sidewall.

[0059] In this embodiment, the initial tilt angle The initial tilt angle is the angle between the emission direction of the exposure light source and the horizontal plane / substrate surface. This is configured for adjusting the exposure equipment. Based on the established coordinate system and the predetermined positions of the photomask and substrate in the corresponding coordinate system, the initial coordinates of the marker points can be determined. These marker points can include one or more, ensuring that the photomask is in the corresponding preset position at the initial coordinates. After preparing the initial tilt angle and initial coordinates, the sidewalls can be exposed according to the predetermined exposure method.

[0060] During tilt exposure, the vertical deviation of the pattern position is controlled by horizontal mechanical movement. The first actual exposure area, formed after the first development, is determined by calculating the distance between the end of the first actual exposure area and the end of the sidewall to be exposed. The exposure area can be identified through the development operation. After identifying the first actual exposure area, the distance between the end of the first actual exposure area and the end of the sidewall to be exposed can be measured, thereby determining the specific size and position of the first actual exposure area. This distance may include the distance between the upper / lower end of the first actual exposure area and the upper / lower end of the sidewall to be exposed.

[0061] In one embodiment, step 4, based on the first actual exposure area and the target exposure area, determines the corrected exposure parameters by correcting the initial exposure parameters, including: determining the exposure deviation area based on the first actual exposure area and the target exposure area; keeping the initial tilt angle unchanged, determining the corrected coordinates of the marker point based on the exposure deviation area and the initial tilt angle, wherein the corrected exposure parameters include the corrected coordinates and the initial tilt angle.

[0062] In this embodiment, the exposure deviation area refers to the vertical misalignment between the first actual exposure area and the target exposure area. In tilted exposure, the light hits the side wall at an angle. If the upper edge (and / or lower edge) of the actual exposed pattern does not coincide with the preset target position, and there is a gap or overlap in the vertical distance, this is the exposure deviation area.

[0063] Given the first actual exposure area and initial exposure parameters, the corrected exposure parameters required when the second actual exposure area is the target exposure area can be calculated. Compared to the initial exposure parameters, the corrected exposure parameters can change one or more parameters, such as the exposure tilt angle and the coordinates of the marker points.

[0064] In this embodiment, based on the first actual exposure area formed under the initial coordinates and initial tilt angle, the coordinate position of the marker point can be calculated to form the second actual exposure area while keeping the tilt angle of the light source constant. This coordinate position is the corrected coordinate. The corrected exposure parameters can be formed from the calculated corrected coordinates and the initial tilt angle.

[0065] Specifically, the corrected coordinates can be achieved by changing parameters in one or more dimensions: the Z-axis (height), X-axis (horizontal), and Y-axis (horizontal). For example, only the parameters in the X-axis (horizontal) and Y-axis (horizontal) directions can be changed, while keeping the parameters in the height direction unchanged. Here, the X-axis (horizontal) direction represents the arrangement direction of the grooves.

[0066] Assuming the vertical height difference of the exposure deviation area is While keeping the tilt angle of the light source and the height of the photomask constant, the photomask (or sample) needs to be moved horizontally by a certain distance. Then the corrected coordinates in the horizontal direction of the X-axis = the initial coordinates. .

[0067] In one embodiment, determining the corrected exposure parameters based on the first actual exposure area and the target exposure area includes: determining an exposure deviation area based on the first actual exposure area and the target exposure area; keeping the initial coordinates of the marker point unchanged, and determining a corrected tilt angle based on the exposure deviation area and the initial coordinates, wherein the corrected exposure parameters include the initial coordinates and the corrected tilt angle.

[0068] Similarly, the position of the photomask can be kept unchanged, and the tilt angle of the exposure light source can be changed to match (coincide with) the target exposure area. The changed tilt angle is the corrected tilt angle, and the corrected exposure parameters can be formed from the corrected tilt angle and the initial coordinates.

[0069] Similarly, assuming the vertical height difference of the exposure deviation area is... The horizontal spacing is At this point, the tilt angle adjustment amount needs to be changed. The corrected tilt angle can be obtained based on this adjustment amount and the initial tilt angle.

[0070] In one embodiment, determining the exposure deviation region based on the first actual exposure region and the target exposure region includes: calculating the deviation distance between the edge position of the first actual exposure region and the edge position of the target exposure region. The step of determining the corrected coordinates of the marker point based on the exposure deviation area and the initial tilt angle includes: according to the formula Calculate the distance to be corrected for the marker points along the horizontal arrangement direction of multiple sidewalls. Based on the distance to be corrected The corrected coordinates of the marker point are determined from the initial coordinates.

[0071] In this embodiment, as Figure 3 As shown, Figure 3 (p1) and (f1) show schematic views of the changes in the positional relationship between the photomask and the substrate in the X-axis direction and the Y-axis direction, respectively, before and after the position adjustment. Figure 3 (p2) and (f2) in the figure show schematic views of the changes in the positional relationship between the photomask and the substrate in the Z-axis direction and the X-axis direction before and after the position adjustment. Figure 3 Compared to the original (p1) and (p2), the adjusted (f1) and (f2) maintain the same exposure angle and Z-axis height of the photomask, but change the correction distance d2 on the X-axis. At position (p1), the alignment marks on the photomask and the corresponding marks on the sample (substrate) are completely coincident, and the coordinates of the marking points are the initial coordinates.

[0072] According to the positional relationship shown in (p1) and (p2), when the light source is tilted at the initial angle... When light shines through the photomask pattern on the photomask, it is projected onto the sidewall of the sample, thus obtaining the first actual exposure area. Based on the positional deviation between the first actual exposure area and the target exposure area, the deviation distance d1 between their upper edges can be obtained. Based on this d1 and... Then you can follow the formula Calculate the distance to be corrected for the marker points along the horizontal arrangement of multiple trenches. This is the error value measured after the first exposure.

[0073] like Figure 3 As shown in (f1) and (f2), the photomask is translated horizontally along the X-axis. The coordinates of the marked point on the photomask after the position is moved are the corrected coordinates. At this position, exposure is continued using the initial tilt angle, resulting in the second actual exposure area coinciding with the target exposure area.

[0074] In one embodiment, determining the exposure deviation region based on the first actual exposure region and the target exposure region includes: calculating the deviation distance between the edge position of the first actual exposure region and the edge position of the target exposure region. The step of determining the correction tilt angle based on the exposure deviation area and the initial coordinates includes: based on trigonometric relationships, according to the deviation distance... Initial tilt angle The positional relationship between the marked points and the corresponding sidewalls under the initial coordinates is used to calculate the corrected tilt angle.

[0075] In this embodiment, the coordinate positions of the substrate and photomask can be kept unchanged, but the exposure tilt angle can be altered to make the area formed by the second exposure coincide with the target exposure area. Let the deviation distance d1 = L1 - L0, where L1 represents the first distance between the upper edge of the first actual exposure area and the upper end of the sidewall, and L0 represents the target distance between the upper edge of the target exposure area and the upper end of the sidewall. If... A positive expression indicates that the actual exposure area is lower than the target exposure area, and it needs to be corrected upwards; if... A negative value indicates that the actual position is higher than the target and needs to be corrected downwards.

[0076] The light rays at the initial tilt angle Incident light is incident on the photomask, with the marked point at the initial coordinates. Let the distance between the marked point and the sidewall to be exposed in the horizontal X-axis direction be denoted as... The irradiation height at the first exposure Target exposure area height . This represents the distance in the height direction between the lower surface of the photomask and the upper end of the first actual exposure area; This represents the distance in the height direction between the lower surface of the photomask and the upper end of the target exposure area. The tilt angle is corrected based on trigonometric relationships. satisfy ,Will Substituting it in, we get Thus, the corrected tilt angle is obtained. .

[0077] By quantizing the exposure results and calculating and adjusting the corrected coordinates of the marker points or the light correction tilt angle, the corrected exposure parameters can be obtained quickly and accurately.

[0078] In one embodiment, the initial tilt angle includes multiple angles, or the initial tilt angle is a variable angle; controlling the tilt exposure device to expose the sidewall to be exposed according to the initial tilt angle includes: controlling the tilt exposure device to expose the sidewall to be exposed according to different initial tilt angles, such that the initial tilt angle used when exposing the lower edge of the first actual exposure area of ​​the sidewall to be exposed is greater than the initial tilt angle used when exposing the upper edge of the first actual exposure area of ​​the sidewall to be exposed.

[0079] A smaller tilt angle allows for exposure of the sidewall closer to a perpendicular illumination method, resulting in an exposure area that is more rectangular and closely resembles the desired shape. Due to the aspect ratio of the trench, the minimum acceptable tilt angle near the lower edge of the exposure area is greater than that near the upper edge. By continuously adjusting the tilt exposure angle and setting different initial tilt angles for different exposure positions, the smallest possible initial tilt angle can be used within the allowable range, ensuring that the shape of the resulting exposure area closely matches the target exposure shape.

[0080] After determining the initial tilt angle corresponding to different exposure positions, the first exposure is performed according to the steps described above. The corresponding corrected exposure parameters are then calculated based on the obtained first actual exposure area, initial tilt angle, and coordinate position. Optionally, the corrected exposure parameters can be adjusted for one or more of the initial tilt angle and the coordinate position of the marked point.

[0081] In one embodiment, taking multiple initial tilt angles, including an initial first tilt angle and an initial second tilt angle, as an example, the exposure area can also be divided into a first sub-region and a second sub-region, with different tilt angles used for exposure in different sub-regions. The control of the tilt exposure device to expose the sidewall to be exposed according to the initial tilt angle includes: controlling the tilt exposure device to expose the first sub-region of the first actual exposure area according to the initial first tilt angle, and controlling the tilt exposure device to expose the second sub-region of the first actual exposure area according to the initial second tilt angle, wherein the first sub-region is located below the second sub-region, and the first tilt angle is greater than the second tilt angle.

[0082] In this embodiment, the sidewall exposure, which originally needed to be completed in one go, is broken down into independent exposure processes for different depth regions. First, the sidewall to be exposed is divided into multiple sub-regions in the vertical direction. For example, it can be divided into a first sub-region (below) and a second sub-region (above). Then, for the first sub-region (below): a large initial first tilt angle is set. Set a small initial second tilt angle for the second sub-region (above). Different tilt angles were used for exposure in the different areas mentioned above. Specifically, the first exposure mainly targeted the first sub-region below the chute, using... Irradiating this area at a large angle allows the light to reach the bottom of the tank, while the second sub-area above may not be fully exposed due to an excessively large angle or obstruction; then, using... Expose the second sub-region above the sloping groove. At this time, the light mainly acts on the upper middle part of the side wall without excessively interfering with the already processed bottom.

[0083] By dividing the sidewall into different regions and illuminating each region with light at different initial tilt angles, the shape of the actual exposure area formed can be made closer to the target exposure shape.

[0084] In one embodiment, step 1 involves using an etching process to create grooves in the substrate, forming multiple trenches.

[0085] For example, p-type monocrystalline silicon is selected as the substrate, the substrate has a crystal orientation of 100° and a resistivity of 1-3. The substrate was grooved using Bosch's Deep Reactive Ion Etching (DRIE) process. The etching reagent was a C4F8 / SF6 mixed gas with a mixing ratio of C4F8:SF6 = 5:1-3:1 (volume ratio). The etching temperature was controlled between -10℃ and 25℃, and the etching depth was... Etching opening width ; The initial tilt angle of the light source; the verticality of the sidewall is 88°-90°, and the sidewall roughness is less than 100. .

[0086] In step 2, the substrate after grooving is subjected to adhesion enhancement treatment. Ultrasonic atomization spraying is used to spray adhesive onto the substrate, and the sprayed photoresist is positive photoresist.

[0087] For example, a positive photoresist can be used, which needs to meet the requirements of high sidewall coverage, low surface tension, and good deep trench filling. The positive photoresist is diluted in a dust-free environment to adjust the viscosity to 100-150. After configuration, let it stand for 30 minutes. Remove air bubbles from the adhesive; apply the adhesive to the substrate using ultrasonic atomization spraying, with the spraying pressure controlled between 0.1 and 0.3. The distance between the nozzle and the substrate is 35. The number of cycles is 5-8, and the adhesive layer thickness is controlled at 3-5 mm. After the adhesive is applied, the substrate undergoes a pre-baking treatment at a temperature of 60℃–90℃ for 5–10 minutes. .

[0088] Furthermore, the HMDS adhesion enhancement treatment employs a vacuum evaporation method. The substrate is placed in a vacuum evaporation chamber, HMDS vapor is introduced, and a vacuum level of 50-100 is maintained. Temperature controlled at 120℃, processing time 10-15 minutes. After treatment, the water contact angle on the substrate surface is greater than or equal to 65°.

[0089] In steps 3 to 5, the substrate sidewalls are exposed to a light source at a preset initial tilt angle to ensure uniform exposure and guarantee the accuracy of the sidewall pattern. During exposure, the distance between the photomask and the sample remains constant. Through XY horizontal rotation and translation operations, the photomask is completely aligned with the alignment marks on the substrate (e.g., ...). Figure 3 As shown in (p1), the marked points on the photomask are positioned at their corresponding initial coordinates, followed by the first exposure. After exposure, the substrate is developed, and the distance between the first actual exposure area and the upper edge of the first actual exposure area (window) and the upper edge of the substrate sidewall is precisely measured (d1). Then, the distance d2 that the photomask / substrate needs to move in the X-axis direction for the second exposure is calculated according to the corresponding formula, thus obtaining the corrected exposure parameters. After measurement, the substrate is cleaned, and after passing the cleaning, it is sprayed with adhesive again using ultrasonic atomization (the adhesive spraying parameters are the same as the first spraying). Then, the second exposure is carried out according to the corrected exposure parameters. Before the second exposure, the alignment marks on the photomask and the sample are completely aligned again. Then, the sample is moved back and forth along the horizontal direction of the X-axis until the difference between the scales of the two is observed to be the required movement distance d2, and then the exposure operation is performed.

[0090] Furthermore, the cleaning after the first exposure is performed using deionized water ultrasonic cleaning, with the ultrasonic power controlled at 30-50W and the cleaning time at 10-15s. After cleaning, the surface is dried with nitrogen to avoid residual impurities affecting the effect of the second adhesive spraying, ensuring that the adhesive layer is uniform and flawless after the second adhesive spraying.

[0091] In step 61, the substrate after the second exposure is immersed and developed using a positive photoresist developer, and the immersed substrate is dried using nitrogen gas.

[0092] In this embodiment, the positive photopolymer developer is an aqueous solution of TMAH (tetramethylammonium hydroxide) with a concentration of 2.38%. Immersion development is used for development, and the development parameters are controlled as follows: temperature 23℃±1℃, development time 120-180s. After development, the sample is post-processed by rinsing with deionized water for 30-60s to remove residual developer, and then drying with nitrogen to ensure that the sample surface is dry and free of residue.

[0093] In step 62, Ti or Au metal is selected, and magnetron sputtering is used to sputter the substrate after the second development.

[0094] In this embodiment, Ti, Au, and other metals are selected as the metal materials; magnetron sputtering is used for sputtering, and the process parameters are controlled as follows: power is DC 50–300W and RF 100–500W; the sputtering environment is an Ar atmosphere, and the pressure is controlled at 0.3–1. Sputtering temperature should be controlled below 120℃ to avoid thermal deformation of the photoresist.

[0095] In step 63, NMP is selected as the stripping agent, and an ultrasonic-assisted immersion process is used to strip the substrate after sputtering metal.

[0096] In this embodiment, an ultrasonic-assisted immersion process is used, and NMP (N-methylpyrrolidone) is selected as the stripping agent; the process parameters are controlled as follows: temperature 60℃–85℃, stripping time 5–30 minutes. Simultaneously, ultrasonic-assisted accelerated peeling is employed, with an ultrasonic power of 50–100W and an ultrasonic frequency of 40kHz; peeling integrity control requirements: the sample is pre-soaked in the peeling solution for 5–10 minutes. The photoresist is fully swollen; then, with the aid of ultrasound, the metal film is broken along the edge of the photoresist to avoid metal residue; after the stripping is completed, the sample is cleaned with IPA or deionized water in sequence, and finally dried with nitrogen to ensure that the substrate and trench are undamaged and free of metal residue.

[0097] In one embodiment, a semiconductor device is provided, which is prepared by the exposure method described above.

[0098] In one embodiment, an electronic device is also provided, including the aforementioned semiconductor device.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0100] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for patterning the side metal of a substrate, characterized in that, The method includes: Step 1, providing a substrate, wherein the substrate has sidewalls; Step 2: Prepare a pattern transfer medium on the substrate to form a photoresist layer covering the sidewalls; Step 3: For the target exposure area covered by photoresist layer on the sidewall, the first exposure is performed using the tilt exposure method according to the preset initial exposure parameters to form the first actual exposure area. The initial exposure parameters include the initial tilt angle and the initial coordinates of the marked points on the photomask. Step 4: Based on the first actual exposure area and the target exposure area, correct the initial exposure parameters and determine the corrected exposure parameters; Step 5: Perform a second tilt exposure according to the corrected exposure parameters, so that the second actual exposure area obtained by the second tilt exposure is consistent with the target exposure area; Step 6: Perform metal patterning operation to form a metal pattern in the second actual exposure area; The method of using tilt exposure to perform the first exposure according to preset initial exposure parameters to form the first actual exposure area includes: placing the photomask on the substrate at a preset position, so that the marked point is at the corresponding initial coordinate, exposing the target exposure area according to the initial tilt angle, and determining the distance between the end of the first actual exposure area and the end of the corresponding sidewall. The step of determining the corrected exposure parameters based on the first actual exposure area and the target exposure area includes: determining the exposure deviation area based on the first actual exposure area and the target exposure area; Keeping the initial tilt angle constant, the corrected coordinates of the marker point are determined based on the exposure deviation area and the initial tilt angle. The corrected exposure parameters include the corrected coordinates and the initial tilt angle; or Keeping the initial coordinates of the marked point unchanged, a corrected tilt angle is determined based on the exposure deviation area and the initial coordinates. The corrected exposure parameters include the initial coordinates and the corrected tilt angle.

2. The method according to claim 1, characterized in that, Determining the exposure deviation region based on the first actual exposure region and the target exposure region includes: calculating the deviation distance between the edge position of the first actual exposure region and the edge position of the target exposure region. ; The step of determining the corrected coordinates of the marker point based on the exposure deviation area and the initial tilt angle includes: according to the formula Calculate the distance to be corrected for the marker points along the horizontal arrangement direction of multiple sidewalls. Based on the distance to be corrected The corrected coordinates of the marker point are determined from the initial coordinates.

3. The method according to claim 1, characterized in that, Determining the exposure deviation region based on the first actual exposure region and the target exposure region includes: calculating the deviation distance between the edge position of the first actual exposure region and the edge position of the target exposure region. ; The step of determining the corrected tilt angle based on the exposure deviation area and the initial coordinates includes: based on trigonometric relationships, according to the deviation distance... Initial tilt angle The positional relationship between the marked points and the corresponding sidewalls under the initial coordinates is used to calculate the corrected tilt angle.

4. The method according to any one of claims 1 to 3, characterized in that, The initial tilt angle may include multiple angles, or the initial tilt angle may be a variable angle; The exposure processing of the target exposure area according to the initial tilt angle includes: exposing the target exposure area according to different initial tilt angles, such that the initial tilt angle used to form the lower edge of the first actual exposure area is greater than the initial tilt angle used to form the upper edge of the first actual exposure area.

5. The method according to any one of claims 1 to 3, characterized in that, The metal patterning operation, which forms a metal pattern in the second actual exposure area, includes: Step 61: Develop the second actual exposure area to form a sidewall metal window pattern; Step 62: Sputter metal onto the developed substrate to form the target metal layer; Step 63: The substrate after sputtering metal is stripped to form a metal pattern.

6. The method according to claim 5, characterized in that, In step 1, an etching process is used to create grooves in the substrate to form multiple grooves including sidewalls. In step 2, the substrate after grooving is subjected to an adhesive enhancement process. The pattern transfer medium is covered to the sidewall by ultrasonic atomization spraying. The pattern transfer medium is positive photoresist. In step 61, the substrate after the second exposure is immersed and developed using a positive photoresist developer, and the immersed substrate is dried using nitrogen gas. In step 62, Ti or Au metal is selected, and magnetron sputtering is used to sputter the developed substrate. In step 63, NMP is selected as the stripping agent, and an ultrasonic-assisted immersion process is used to strip the substrate after sputtering metal.

7. A semiconductor device prepared according to any one of claims 1 to 6.

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