Etching method and device for photoresist morphology modification and semiconductor device
By depositing an organic passivation layer on the photoresist surface and performing selective etching, the problem of steep deviation of the side wall of the photoresist is solved, and the performance and yield of the semiconductor device are improved.
Patent Information
- Application Number
- CN202411442516.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-16
- Publication Date
- 2025-02-25
AI Technical Summary
In semiconductor micro-nano processing, the steepness of the side wall of the photoresist deviates from the ideal morphology, affecting the performance and yield of the device.
By an etching method for photoresist morphology modification, it includes depositing an organic passivation layer on the photoresist surface and selectively consuming the photoresist through the action of the lower electrode radio frequency power supply during the cyclic etching process to improve the straightness of the side wall.
The steepness of the photoresist side wall is achieved, the quality and accuracy in the manufacturing process is improved, and the defects and defects of the device are reduced.
Smart Images
Figure CN119517742A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to an etching method, apparatus and semiconductor device for photoresist morphology modification. Background Technology
[0002] In semiconductor micro- and nano-fabrication, photolithography and etching processes are combined for pattern transfer. The steepness of the sidewalls of the photoresist directly affects the morphology of the etched device, thus impacting its performance and yield.
[0003] However, in actual photolithography, factors such as light scattering, mask contact, and differences in photoresist thickness cause the photoresist sidewalls to deviate from the ideal morphology, thus affecting the final result.
[0004] Therefore, improving the steepness of the photoresist sidewalls has become an urgent problem to be solved. Summary of the Invention
[0005] This application provides an etching method, apparatus, and semiconductor device for modifying the morphology of photoresist, which solves the technical problem that the steepness of the photoresist sidewalls deviates from the ideal morphology, and achieves the technical effect of improving the steepness of the photoresist sidewalls.
[0006] To achieve the above objectives, the main technical solutions adopted in this application include:
[0007] In a first aspect, embodiments of this application provide an etching method for modifying the morphology of photoresist, the method comprising:
[0008] A target silicon wafer is obtained after preliminary photolithography, the target silicon wafer having photoresist to be corrected, the surface of the photoresist including a horizontal plane and a slope;
[0009] The photoresist is subjected to cyclic etching; each cyclic etching process includes a deposition stage and a consumption stage; the deposition stage is used to deposit an organic passivation layer on the surface of the photoresist, wherein the amount of the organic passivation layer deposited per unit area on the horizontal plane is greater than the amount deposited per unit area on the inclined plane; the consumption stage is used to consume the photoresist in a direction perpendicular to the horizontal plane under the action of the lower electrode RF power supply, and under the action of the organic passivation layer, the amount of photoresist consumed on the inclined plane is greater than the amount of photoresist consumed on the horizontal plane.
[0010] This embodiment provides an etching method for modifying the morphology of photoresist. An organic passivation layer can be deposited on both horizontal and inclined surfaces of the photoresist. During this process, the amount of organic passivation layer deposited on the horizontal surface is greater than that on the inclined surface. Subsequently, during cyclic etching of the photoresist, the organic passivation layer enables selective consumption of the photoresist. Specifically, the horizontal surface with a larger organic passivation layer deposition consumes relatively less photoresist, while the inclined surface with a smaller organic passivation layer deposition consumes relatively more photoresist. This uneven consumption helps to improve the steepness of the photoresist sidewalls. Therefore, the technical solution provided in this embodiment exhibits non-uniformity in the deposition of the organic passivation layer on the photoresist surface, and the different consumption rates of the photoresist on the horizontal and inclined surfaces during cyclic etching further correct the steepness of the photoresist sidewalls. Overall, this method achieves high-precision photoresist pattern correction through cyclic etching that includes deposition and consumption stages, improving the quality and accuracy of the manufacturing process.
[0011] Optionally, before cyclically etching the photoresist, the method further includes:
[0012] An initial deposition of an organic passivation layer is performed on the photoresist, wherein the organic passivation layer in the initial deposition process and the organic passivation layer in the cyclic etching process are both obtained by polymerization of carbon difluoride ions ionized from carbon fluoride plasma, and a specified amount of oxygen is added to the carbon fluoride plasma during the ionization process.
[0013] Accordingly, the photoresist after initial deposition is cyclically etched.
[0014] In this embodiment, carbon difluoride ions ionized by carbon fluoride-based plasma are deposited on the photoresist surface to form an organic passivation layer, resulting in a protective film of uniform thickness. This protective film provides different levels of protection on both the horizontal and inclined surfaces of the photoresist. The addition of oxygen during ionization helps stabilize the plasma and remove carbon components from the photoresist, improving etching selectivity and control precision. Therefore, during cyclic etching, the initially deposited organic passivation layer effectively reduces consumption on the horizontal surface of the photoresist, preferentially accelerating etching on the inclined surface, thereby improving the morphology and selectivity of the photoresist and enhancing the final etching precision and efficiency.
[0015] Optionally, the first duration of the initial deposition process is longer than the second duration of the deposition phase during a single etching process, and the first power of the inductively coupled plasma applied during the initial deposition process is higher than the second power of the inductively coupled plasma applied during the deposition phase.
[0016] This embodiment ensures the formation of a thicker organic passivation layer on the photoresist surface by extending the initial deposition process for a longer duration than the second duration of the deposition phase during a single etching process. This thickness helps provide more effective protection during subsequent etching processes, especially on the horizontal surface of the photoresist. Simultaneously, the first power of the inductively coupled plasma applied during the initial deposition process is higher than the second power of the inductively coupled plasma applied during the deposition phase. This allows for the rapid formation of a uniform and thicker organic passivation layer during the initial deposition phase, while the lower power during cyclic etching is used to maintain etching stability and selectivity. During the etching phase, because the organic passivation layer is thinner on the slope, the photoresist consumption on the slope is greater than on the horizontal surface, thus achieving a steeper slope morphology.
[0017] Optionally, the lower electrode RF power supply is not turned on during the initial deposition process and during the deposition stage of one etching process.
[0018] This embodiment helps form a uniform organic passivation layer on the photoresist surface by not turning on the lower electrode RF power supply during the initial deposition process and the deposition stage of the first etching process, rather than through high-energy physical bombardment. This low-energy environment helps form a high-quality organic passivation layer, providing better protection for subsequent etching processes.
[0019] Optionally, during the initial deposition process, the flow rate of the fluorinated carbon plasma is 35 sccm, the flow rate of the oxygen is 8 sccm, the first duration of the initial deposition process is 20 s, the first power of the inductively coupled plasma applied during the initial deposition process is 500 W, and the pressure in the reaction chamber during the initial deposition process is 20 mTorr.
[0020] In this embodiment, a uniform organic passivation layer can be formed on the photoresist surface by setting the flow rate of the fluorinated carbon plasma to 35 sccm. The fluorinated carbon gas reacts with oxygen in the plasma state to generate (CF2). n Long-chain polymers are deposited on the photoresist surface. Setting the oxygen flow rate to 8 sccm helps modulate the chemical reactions in the plasma, ensuring (CF2) nThe formation reaction of the long-chain polymer proceeds effectively without excessive oxidation. Setting the initial deposition process duration to 20 seconds ensures sufficient reaction time to form the desired organic passivation layer thickness while preventing over-deposition due to excessive deposition time. Applying an inductively coupled plasma with an initial power of 500W helps generate a high-density plasma, thereby improving the deposition rate and the quality of the organic passivation layer. Maintaining a pressure of 20 mTorr within the reaction chamber helps maintain plasma stability, ensuring that active particles in the plasma can effectively participate in the deposition process. Consequently, the organic passivation layer is deposited less on the beveled surfaces of the photoresist and more on the horizontal surfaces, which helps protect the horizontal surfaces of the photoresist during subsequent etching while accelerating the etching of the beveled surfaces, thus achieving a steep morphology of the photoresist bevel.
[0021] Optionally, during the deposition stage, fluorinated carbon plasma and oxygen are injected into the reaction chamber where the target silicon wafer is located; during the consumption stage, only oxygen is injected into the reaction chamber, and the flow rate of the oxygen injected during the consumption stage is higher than that of the oxygen injected during the deposition stage.
[0022] In this embodiment, the co-injection of fluorinated carbon plasma and oxygen during the deposition stage helps stabilize plasma ignition and form a uniform organic passivation layer on the photoresist surface. This passivation layer protects the photoresist from excessive erosion during subsequent etching processes, especially for horizontal areas. Injecting only oxygen during the consumption stage allows for a more focused approach to removing the photoresist through physical bombardment and chemical reactions. This enables more precise control of the etching process, resulting in clearer patterns. Further increasing the oxygen flow rate increases the etching rate of beveled photoresist, while the etching rate is relatively lower on horizontal surfaces due to the thicker organic passivation layer. This differential etching contributes to a steeper photoresist bevel.
[0023] Optionally, the duration of the consumption phase is longer than the duration of the deposition phase, and the power of the inductively coupled plasma applied during the consumption phase is lower than the power of the inductively coupled plasma applied during the deposition phase.
[0024] This embodiment, by extending the duration of the consumption phase beyond the deposition phase, facilitates more precise control over the photoresist etching process, particularly the morphology of the photoresist bevels, resulting in steeper sidewalls and thus improving device accuracy and performance. Furthermore, by applying a lower power of the inductively coupled plasma during the consumption phase compared to the deposition phase, over-etching of the photoresist and thermal damage are reduced.
[0025] Optionally, in the deposition stage, the flow rate of the fluorinated carbon plasma is 35 sccm, the flow rate of oxygen is 8 sccm, the duration of the deposition stage is 3 s, and the power of the inductively coupled plasma applied during the deposition stage is 300 W; in the consumption stage, the flow rate of oxygen is 40 sccm, the duration of the consumption stage is 5 s, the power of the inductively coupled plasma applied during the consumption stage is 200 W, and the power of the lower electrode radio frequency power supply applied during the consumption stage is 50 W; the pressure in the reaction chamber during both the deposition stage and the consumption stage is 20 mTorr.
[0026] In this embodiment, by using a fluorinated carbon plasma flow rate of 35 sccm and an oxygen flow rate of 8 sccm during the deposition stage, combined with an inductively coupled plasma power of 300W and a duration of 3 seconds, a high-quality organic passivation layer can be rapidly and uniformly formed on the photoresist surface. Subsequently, in the consumption stage, by increasing the oxygen flow rate to 40 sccm and reducing the inductively coupled plasma power to 200W, while applying a 50W lower electrode RF power supply, a gentler and finer etching process can be performed over a longer period of 5 seconds. This helps to achieve a steep morphology of the photoresist bevel while reducing thermal damage. The entire process is carried out at a pressure of 20 mTorr, ensuring plasma stability and process consistency. This not only improves etching selectivity and yield but also reduces production costs.
[0027] Optionally, obtaining the target silicon wafer after preliminary photolithography includes:
[0028] For the silicon wafer to be processed, ultrasonic cleaning and plasma cleaning are performed respectively.
[0029] After cleaning, the silicon wafer is coated with adhesive and photoresist in sequence, and then preheated.
[0030] The preheated silicon wafer is subjected to ultraviolet exposure and development, and the developed silicon wafer is then subjected to hardening for a specified duration.
[0031] The silicon wafer after hardening is lowered to a specified temperature to obtain the target silicon wafer after preliminary photolithography.
[0032] This embodiment first performs ultrasonic cleaning and plasma cleaning on the silicon wafer to be processed to ensure that the surface of the silicon wafer is free of contaminants. Next, an adhesive and photoresist are uniformly applied to the cleaned silicon wafer, followed by preheating to improve material adhesion. The preheated silicon wafer undergoes ultraviolet exposure and development to form the desired pattern, followed by a hardening process of a specified duration to optimize the morphology and uniformity of the film. Finally, the hardened silicon wafer is cooled to a specified temperature to obtain the target silicon wafer after preliminary photolithography. Through effective cleaning, coating, exposure, and processing steps, the efficiency and accuracy of the photolithography process are ensured, ultimately achieving a high-quality photolithography effect.
[0033] Secondly, embodiments of this application provide an etching apparatus for modifying the morphology of photoresist, the apparatus comprising:
[0034] A silicon wafer acquisition unit is used to acquire a target silicon wafer after preliminary photolithography. The target silicon wafer has photoresist to be corrected, and the surface of the photoresist includes a horizontal plane and a slope.
[0035] A cyclic etching unit is used to cyclically etch the photoresist. Each cyclic etching process includes a deposition stage and a consumption stage. The deposition stage is used to deposit an organic passivation layer on the surface of the photoresist, wherein the amount of the organic passivation layer deposited per unit area on the horizontal plane is greater than the amount deposited per unit area on the inclined plane. The consumption stage is used to consume the photoresist in a direction perpendicular to the horizontal plane under the action of the lower electrode RF power supply, and under the action of the organic passivation layer, the amount of photoresist consumed on the inclined plane is greater than the amount consumed on the horizontal plane.
[0036] Thirdly, embodiments of this application provide a semiconductor device, which is fabricated based on the etching method for photoresist morphology modification described above. Attached Figure Description
[0037] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0038] Figure 1 A flowchart of an etching method for modifying photoresist morphology provided in an embodiment of this application;
[0039] Figure 2 A schematic cross-sectional view of the target silicon wafer after preliminary photolithography, provided for an embodiment of this application;
[0040] Figure 3 A flowchart prior to step S3 is provided for an embodiment of this application;
[0041] Figure 4 A flowchart for obtaining a target silicon wafer after preliminary photolithography, provided as an embodiment of this application;
[0042] Figure 5 A flowchart following step S3 is provided for an embodiment of this application;
[0043] Figure 6 A schematic diagram illustrating the cross-sectional changes of the target silicon wafer after cyclic etching, provided in an embodiment of this application;
[0044] Figure 7 This is a schematic diagram of the cross-section of AZ1512 photoresist after development under different exposure doses;
[0045] Figure 8 This is a cross-sectional view of the photoresist after cyclic etching modification, observed using a scanning electron microscope.
[0046] Figure 9 This is a block diagram of an etching apparatus for photoresist morphology modification provided in an embodiment of this application.
[0047] Explanation of reference numerals in the attached figures
[0048] 111 - Target silicon wafer, 112 - Photoresist, 113a - Horizontal surface of photoresist before correction, 114a - Horizontal surface of photoresist before correction, 113b - Horizontal surface of photoresist after correction, 114b - Sloping surface of photoresist after correction. Detailed Implementation
[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0050] In semiconductor micro-nano fabrication processes, photolithography and etching are often used in combination to complete pattern transfer. However, the steepness of the photoresist sidewalls directly affects the final morphology of the etched device, which in turn has a significant impact on device performance and product yield. Ideally, both sidewalls should be steep, but in actual photolithography processes, factors such as light scattering, mask contact distance, and photoresist thickness differences can cause the photoresist sidewalls to deviate from the ideal steep morphology.
[0051] The ultraviolet lithography machines commonly used in laboratories employ mercury lamps as light sources. The long wavelength of this light causes diffraction and scattering during the lithography process, resulting in uneven exposure of the photoresist in both horizontal and vertical directions. Mechanical contact between the photomask and the silicon substrate can also cause light scattering in areas not covered by the metal coating on the photomask, leading to uneven photoresist exposure. Dry etching follows immediately after lithography, and issues with the selection of photoresist and etching materials often result in poor photosensitivity at the bottom of the photoresist, leading to steeper sidewalls after development. To address this problem, researchers typically employ a multi-layer photoresist exposure method. This involves exposing each layer of photoresist to different wavelengths of light, reducing the thickness of the photoresist in each exposure and making the photosensitivity more uniform, thus achieving steeper sidewalls after development. However, while this technique improves sidewall steepness, the repeated steps of homogenization, drying, and exposure increase the complexity, economic cost, and time cost of production.
[0052] To address the aforementioned technical problems, according to an embodiment of this application, an etching method for modifying photoresist morphology is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.
[0053] This embodiment provides an etching method for modifying the morphology of photoresist. Figure 1 A flowchart of an etching method for modifying photoresist morphology provided in this application embodiment is shown below. Figure 1 As shown, the process includes the following steps:
[0054] Step S1: Obtain the target silicon wafer after preliminary photolithography. The target silicon wafer has photoresist to be corrected. The surface of the photoresist includes a horizontal plane and a slope.
[0055] Please see Figure 2 A schematic cross-sectional view of the target silicon wafer after preliminary photolithography, as provided in the embodiments of this application, is shown below. Figure 2 As shown, the target silicon wafer 111 has a photoresist 112 to be corrected. The surface of the photoresist 112 includes a horizontal photoresist surface 113a and a sloped photoresist surface 114a before correction. That is, the morphology of the photoresist 112 is inclined in the vertical direction. In this specification, the vertical direction is specifically defined as along the depth direction of the photoresist 112. The following descriptions will focus on improving the steepness of the sloped photoresist surface 114a before correction.
[0056] Specifically, the process begins with cleaning the silicon wafer to remove surface impurities and oxide layers, ensuring the photoresist is uniformly coated onto the wafer. Next, spin coating or spray coating methods are used to evenly coat the photoresist onto the silicon wafer surface. After coating, a soft bake (pre-baking) is typically performed to remove solvents from the photoresist and increase the stability of the film. The silicon wafer is then placed in a photolithography machine and exposed through a photomask to form the desired pattern. During exposure, the photoresist undergoes a chemical reaction due to the light. A developer is then used to develop the exposed silicon wafer, dissolving any unexposed or exposed photoresist areas, thereby transferring the pattern from the photomask to the silicon wafer, resulting in the preliminary photolithographically lithographic target silicon wafer.
[0057] Step S3 involves cyclic etching of the photoresist. Each cyclic etching process includes a deposition stage and a consumption stage. The deposition stage is used to deposit an organic passivation layer on the surface of the photoresist, wherein the amount of organic passivation layer deposited per unit area on the horizontal plane is greater than the amount deposited per unit area on the inclined plane. The consumption stage is used to consume the photoresist in a direction perpendicular to the horizontal plane under the action of the lower electrode RF power supply, and under the action of the organic passivation layer, the amount of photoresist consumed on the inclined plane is greater than the amount of photoresist consumed on the horizontal plane.
[0058] The photoresist on the target silicon wafer obtained through the above steps has a slope of approximately 75°, which cannot meet the requirements for a steeper slope. This leads to inaccurate pattern transfer in subsequent processes, affecting device manufacturing. Furthermore, a non-steep slope may cause defects during etching, increasing the proportion of defective products and thus reducing production yield. Therefore, further modification of the photoresist on the target silicon wafer is necessary.
[0059] Specifically, the photoresist needs to be cyclically etched. The etching process includes a deposition stage and a consumption stage. First, during the deposition stage, an organic passivation layer is deposited on the photoresist surface. The main function of the organic passivation layer is to protect the horizontal and inclined surfaces of the photoresist, reducing erosion during subsequent etching processes. The amount of this organic passivation layer deposited per unit area on the horizontal surface is greater than that on the inclined surface. On the horizontal surface, gas flow is more stable, and the contact time between the reactant gas and the horizontal surface is longer, resulting in a relatively faster deposition rate. On the inclined surface, however, gas flow may be disturbed due to the surface angle, reducing the contact time between the reactant gas and the inclined surface, leading to a slower deposition rate. Furthermore, the deposition amount per unit area is also reduced due to the angle between the inclined surface and the horizontal deposition direction. This is because on the inclined surface, the deposited material is affected by gravity and airflow dynamics, leading to reduced deposition efficiency. On the inclined surface, the deposited material may not fully adhere to the surface due to the angle and airflow effects, thus reducing the deposition amount per unit area. Therefore, the difference in deposition amount between the horizontal and inclined surfaces helps protect the photoresist inclined surfaces while reducing excessive consumption of photoresist on the horizontal surfaces. By precisely controlling the deposition conditions, the protective effect of the photoresist inclined surfaces can be optimized, thereby maintaining the integrity and accuracy of the pattern during etching.
[0060] Next, during the consumption phase, plasma is generated using the lower electrode RF power supply to etch the photoresist. Due to the presence of the organic passivation layer, the amount of photoresist consumed during etching on the inclined surface is greater than that on the horizontal surface. This is because the organic passivation layer is thinner on the inclined surface, providing weaker protection against etching, making the photoresist on the inclined surface easier to etch away, resulting in a faster etching rate and a steeper inclined surface.
[0061] Finally, the photoresist is cyclically etched by combining the deposition and consumption stages to achieve a steep photoresist slope and improve the manufacturing accuracy of the device in subsequent manufacturing processes.
[0062] This embodiment provides an etching method for modifying the morphology of photoresist. An organic passivation layer can be deposited on both horizontal and inclined surfaces of the photoresist. During this process, the amount of organic passivation layer deposited on the horizontal surface is greater than that on the inclined surface. Subsequently, during cyclic etching of the photoresist, the organic passivation layer enables selective consumption of the photoresist. Specifically, the horizontal surface with a larger organic passivation layer deposition consumes relatively less photoresist, while the inclined surface with a smaller organic passivation layer deposition consumes relatively more photoresist. This uneven consumption helps to improve the steepness of the photoresist sidewalls. Therefore, the technical solution provided in this embodiment exhibits non-uniformity in the deposition of the organic passivation layer on the photoresist surface, and the different consumption rates of the photoresist on the horizontal and inclined surfaces during cyclic etching further correct the steepness of the photoresist sidewalls. Overall, this method achieves high-precision photoresist pattern correction through cyclic etching that includes deposition and consumption stages, improving the quality and accuracy of the manufacturing process.
[0063] Figure 3 The flowchart provided for the embodiments of this application prior to step S3 may include the following steps:
[0064] Step S21: Initial deposition of an organic passivation layer on the photoresist. The organic passivation layer in the initial deposition process and the organic passivation layer in the cyclic etching process are both obtained by polymerization of carbon difluoride ions ionized by carbon fluoride plasma, and a specified amount of oxygen is added to the carbon fluoride plasma during the ionization process.
[0065] To form an organic passivation layer with differentiated protective effects during subsequent etching cycles and to reduce photoresist consumption, an organic passivation layer needs to be initially deposited on the photoresist surface. This organic passivation layer can produce different protective effects on the horizontal and inclined surfaces of the photoresist, thereby achieving differentiated etching of different areas of the photoresist and ultimately modifying the morphology of the inclined surface of the photoresist.
[0066] Specifically, during the deposition of an organic passivation layer on the photoresist surface, carbon difluoride ions ionized by carbon fluoride plasma polymerize to form (CF2). nLong-chain polymers, similar to Teflon films, can form a protective layer on the photoresist surface. This protective layer reduces photoresist consumption during subsequent etching, especially on horizontal surfaces where greater deposition and a thicker protective layer are achieved. Adding a specific amount of oxygen during ionization stabilizes the ionization process of carbon fluoride plasmas, making plasmas such as C4F8 easier to ionize stably. O2 plasma reacts with the carbon-based components in the photoresist to generate CO2, which helps remove carbon components during etching. By applying a small inductively coupled plasma (ICP) power, the partial pressures of O2 and C4F8 can be precisely controlled, enabling cyclic gentle etching with C4F8+O2 plasma and O2 plasma. This cyclic gentle etching reduces photoresist consumption on horizontal surfaces while accelerating consumption on inclined surfaces, thereby modifying the morphology of the photoresist slope to make it steeper.
[0067] In step S23, the photoresist after initial deposition is cyclically etched.
[0068] and Figure 1 Compared to the illustrated embodiment, this embodiment uses carbon difluoride ions ionized by carbon fluoride-based plasma to deposit an organic passivation layer on the photoresist surface, resulting in a protective film of uniform thickness. This protective film provides different levels of protection on both the horizontal and inclined surfaces of the photoresist. The addition of oxygen during ionization helps stabilize the plasma and remove carbon components from the photoresist, improving etching selectivity and control precision. Therefore, during cyclic etching, the initially deposited organic passivation layer effectively reduces consumption on the horizontal surface of the photoresist, preferentially accelerating etching on the inclined surface, thereby improving the morphology and selectivity of the photoresist and enhancing the final etching precision and efficiency.
[0069] In some embodiments, the first duration of the initial deposition process is longer than the second duration of the deposition phase during a single etching process, and the first power of the inductively coupled plasma applied during the initial deposition process is higher than the second power of the inductively coupled plasma applied during the deposition phase.
[0070] To improve the performance and yield of semiconductor devices, precise control of photoresist consumption is crucial while maintaining the steepness of the photoresist slope. However, achieving precise control of photoresist consumption requires controlling the parameters of the initial deposition process and the deposition stages. Specifically, the first duration of the initial deposition process is longer than the second duration of the deposition stage in a single etching process. This is to ensure the formation of a sufficiently thick organic passivation layer on the photoresist surface, effectively protecting the horizontal plane of the photoresist and reducing its consumption during subsequent etching processes.
[0071] The initial power of the inductively coupled plasma (ICP) applied during the initial deposition stage is higher than the second power applied during the deposition stage. This is to rapidly form a thicker organic passivation layer within a shorter time, allowing for more precise control of photoresist consumption during the etching stage. During cyclic etching, a lower ICP power is used to maintain the stability of the etching process and achieve precise control over photoresist consumption. This control is achieved by adjusting the ICP power and gas partial pressure, resulting in gentle cyclic etching of C4F8+O2 plasma and O2 plasma. This ensures reduced photoresist consumption on horizontal surfaces and accelerated consumption on inclined surfaces, making the photoresist slope steeper and achieving the desired morphology modification.
[0072] and Figure 3 Compared to the illustrated embodiment, this embodiment ensures the formation of a thicker organic passivation layer on the photoresist surface by extending the first duration of the initial deposition process beyond the second duration of the deposition phase during a single etching process. This thickness setting helps provide more effective protection during subsequent etching processes, especially on the horizontal plane of the photoresist. Simultaneously, the first power of the inductively coupled plasma applied during the initial deposition process is higher than the second power of the inductively coupled plasma applied during the deposition phase, enabling the rapid formation of a uniform and thicker organic passivation layer during the initial deposition phase. The lower power during the cyclic etching process is used to maintain etching stability and selectivity. During the etching phase, because the organic passivation layer is thinner on the slope, the photoresist consumption on the slope is greater than on the horizontal plane, thus achieving a steep slope morphology.
[0073] In some embodiments, the lower electrode RF power supply is not turned on during the initial deposition process and during the deposition phase of a single etching process.
[0074] Specifically, turning on the bottom electrode RF power supply generates heat, which may cause thermal damage to the photoresist. Avoiding the use of the bottom electrode RF power supply during the initial deposition process and the deposition phase of the first etching process can reduce thermal stress and maintain the integrity of the photoresist. Therefore, not turning on the bottom electrode RF power supply reduces the energy of ions in the plasma, thereby reducing physical damage to the photoresist, while simultaneously promoting the necessary chemical reactions to help form a uniform organic passivation layer.
[0075] and Figure 3 Compared to the illustrated embodiment, this embodiment, by not activating the lower electrode RF power supply during the initial deposition process and the deposition stage of a single etching process, facilitates the formation of a uniform organic passivation layer on the photoresist surface, rather than through high-energy physical bombardment. This low-energy environment helps form a high-quality organic passivation layer, providing better protection for subsequent etching processes.
[0076] In some embodiments, during the initial deposition process, the flow rate of the fluorinated carbon plasma is 35 sccm, the flow rate of oxygen is 8 sccm, the first duration of the initial deposition process is 20 s, the first power of the inductively coupled plasma applied during the initial deposition process is 500 W, and the pressure in the reaction chamber during the initial deposition process is 20 mTorr.
[0077] Specifically, the parameter settings of the initial deposition process are crucial for forming a high-quality organic passivation layer. Specific flow rates of fluorinated carbon gases such as C4F8 and oxygen contribute to the generation of a stable plasma environment. In this environment, carbon difluoride ions ionized from the fluorinated carbon plasma react with oxygen to form (CF2). n Long-chain polymers are deposited on the photoresist surface to form an organic passivation layer. By controlling the flow rate and initial power of the fluorinated carbon plasma, the deposition rate and the quality of the organic passivation layer can be precisely controlled. A higher initial power helps to quickly form a uniform organic passivation layer, while a shorter initial power helps to control the thickness of the organic passivation layer and avoid over-deposition. Furthermore, initial deposition at a pressure of 20 mTorr optimizes the plasma density and reactivity, resulting in a uniform and dense organic passivation layer on the photoresist surface. By setting these process parameters, in subsequent etching processes, the thinner photoresist bevel areas are etched more quickly, while the thicker photoresist horizontal areas are protected. This differential etching helps to achieve a steep morphology of the photoresist bevels, improving pattern accuracy.
[0078] and Figure 3 Compared to the illustrated embodiment, this embodiment achieves a uniform organic passivation layer on the photoresist surface by setting the flow rate of the fluorinated carbon plasma to 35 sccm. The fluorinated carbon gas reacts with oxygen in the plasma state to generate (CF2). n Long-chain polymers are deposited on the photoresist surface. Setting the oxygen flow rate to 8 sccm helps modulate the chemical reactions in the plasma, ensuring (CF2) nThe formation reaction of the long-chain polymer proceeds effectively without excessive oxidation. Setting the initial deposition process duration to 20 seconds ensures sufficient reaction time to form the desired organic passivation layer thickness while preventing over-deposition due to excessive deposition time. Applying an inductively coupled plasma with an initial power of 500W helps generate a high-density plasma, thereby improving the deposition rate and the quality of the organic passivation layer. Maintaining a pressure of 20 mTorr within the reaction chamber helps maintain plasma stability, ensuring that active particles in the plasma can effectively participate in the deposition process. Consequently, the organic passivation layer is deposited less on the beveled surfaces of the photoresist and more on the horizontal surfaces, which helps protect the horizontal surfaces of the photoresist during subsequent etching while accelerating the etching of the beveled surfaces, thus achieving a steep morphology of the photoresist bevel.
[0079] In some embodiments, during the deposition stage, fluorinated carbon plasma and oxygen are injected into the reaction chamber where the target silicon wafer is located; during the consumption stage, only oxygen is injected into the reaction chamber, and the flow rate of oxygen injected during the consumption stage is higher than that of oxygen injected during the deposition stage.
[0080] Specifically, during the deposition stage, fluorinated carbon gases react with oxygen in a plasma state to generate (CF2). n Long-chain polymers are deposited on the surface of the photoresist. This protective film can provide different levels of protection on both horizontal and inclined surfaces of the photoresist.
[0081] During the consumption phase, the addition of oxygen helps stabilize the plasma during ionization and removes carbon components from the photoresist, improving etching selectivity and control precision. Only oxygen is injected in this phase, and the oxygen flow rate is higher than that in the deposition phase. The aim is to utilize the chemical reactivity of oxygen to accelerate the consumption of the photoresist bevel. Because the organic passivation layer on the bevel is thin, the higher oxygen flow rate can increase the etching rate at the bevel, thus making the photoresist bevel steeper.
[0082] and Figure 1 Compared to the illustrated embodiment, this embodiment, through the co-injection of fluorinated carbon plasma and oxygen during the deposition stage, helps form a uniform organic passivation layer on the photoresist surface. This passivation layer protects the photoresist from excessive erosion during subsequent etching processes, especially for horizontal areas. Injecting only oxygen during the consumption stage allows for a more focused approach to removing the photoresist through physical bombardment and chemical reactions. This enables more precise control of the etching process, resulting in clearer patterns. Further increasing the oxygen flow rate increases the etching rate of the beveled photoresist, while the etching rate is relatively lower on horizontal surfaces due to the thicker organic passivation layer. This differential etching contributes to a steeper photoresist bevel.
[0083] In some embodiments, the duration of the consumption phase is longer than the duration of the deposition phase, and the power of the inductively coupled plasma applied during the consumption phase is lower than the power of the inductively coupled plasma applied during the deposition phase.
[0084] Specifically, the longer duration of the consumption phase compared to the deposition phase means more time for fine-tuning the photoresist during etching. A longer consumption phase facilitates finer etching results, particularly in controlling the morphology of the photoresist bevels. This ensures that more photoresist is consumed on beveled surfaces than on horizontal surfaces, resulting in steeper bevels. Furthermore, the lower power of the inductively coupled plasma applied during the consumption phase compared to the deposition phase contributes to gentler etching, reducing unnecessary damage to the photoresist while maintaining etching uniformity. High power can generate excessive thermal stress on the photoresist and target silicon wafer, leading to material performance degradation or pattern deformation. Lower power reduces the energy of ions in the plasma, thus minimizing physical bombardment of the photoresist.
[0085] and Figure 1 Compared to the illustrated embodiment, this embodiment, by extending the duration of the consumption phase beyond the deposition phase, facilitates more precise control over the photoresist etching process, particularly the morphology of the photoresist bevels, resulting in steeper sidewalls and thus improving device accuracy and performance. Furthermore, by applying a lower power of the inductively coupled plasma during the consumption phase compared to the deposition phase, over-etching of the photoresist and thermal damage are reduced.
[0086] In some embodiments, during the deposition phase, the flow rate of the fluorinated carbon plasma is 35 sccm, the flow rate of oxygen is 8 sccm, the deposition phase lasts for 3 s, and the power of the inductively coupled plasma applied during the deposition phase is 300 W; during the consumption phase, the flow rate of oxygen is 40 sccm, the consumption phase lasts for 5 s, the power of the inductively coupled plasma applied during the consumption phase is 200 W, and the power of the lower electrode radio frequency power supply applied during the consumption phase is 50 W; the pressure in the reaction chamber during both the deposition and consumption phases is 20 mTorr.
[0087] Specifically, during the deposition stage, the flow rate of the fluorinated carbon plasma is 35 sccm, and the flow rate of oxygen is 8 sccm. This gas flow rate combination helps to rapidly form a uniform organic passivation layer on the photoresist surface. The shorter duration of the deposition stage and the higher power of the inductively coupled plasma can accelerate the chemical reaction and promote the formation of the organic passivation layer. By applying an inductively coupled plasma power of 300W during the deposition stage, it can be ensured that the active particles in the plasma have sufficient energy to promote the chemical reaction, thereby forming a high-quality organic passivation layer.
[0088] During the consumption phase, increasing the oxygen flow rate to 40 sccm and reducing the power of the inductively coupled plasma to 200 W facilitates gentler etching, reducing unnecessary damage to the photoresist while maintaining etching uniformity. Furthermore, increasing the oxygen flow rate to 40 sccm means that during the consumption phase, oxygen is used not only for etching the consumed photoresist but also for reacting with residual fluorinated carbon plasma from the deposition phase to generate an organic passivation layer. This allows for simultaneous photoresist removal and organic passivation layer formation during etching, improving process efficiency and product quality. The longer duration of the consumption phase allows more time to fine-tune the photoresist bevel morphology, achieving steeper bevels and improving device performance and yield. The 50 W power applied to the lower electrode RF power supply during the consumption phase primarily provides energy for ion bombardment, which helps accelerate the photoresist etching process, resulting in steeper bevels.
[0089] Maintaining the pressure in the reaction chamber at 20 mTorr throughout the deposition and consumption phases helps maintain plasma stability, thereby improving the stability and repeatability of the entire etching process.
[0090] and Figure 1 Compared to the illustrated embodiment, this embodiment, through a deposition stage using a fluorinated carbon plasma flow rate of 35 sccm and an oxygen flow rate of 8 sccm, combined with an inductively coupled plasma power of 300W and a duration of 3 seconds, can rapidly and uniformly form a high-quality organic passivation layer on the photoresist surface. Subsequently, in the consumption stage, by increasing the oxygen flow rate to 40 sccm and reducing the inductively coupled plasma power to 200W, while simultaneously applying a 50W lower electrode RF power supply, a gentler and finer etching process can be performed over a longer period of 5 seconds. This helps to achieve a steep morphology of the photoresist bevel while reducing thermal damage. The entire process is carried out at a pressure of 20 mTorr, ensuring plasma stability and process consistency. This not only improves etching selectivity and yield but also reduces production costs.
[0091] Figure 4 The flowchart for obtaining a target silicon wafer after preliminary photolithography provided in this application embodiment may include the following steps:
[0092] Step S11: For the silicon wafer to be processed, ultrasonic cleaning and plasma cleaning are performed respectively.
[0093] Specifically, ultrasonic cleaning utilizes the cavitation effect generated by high-frequency sound waves to remove particles or organic matter from the silicon wafer surface, thus removing contaminants without altering the surface's chemical properties. Plasma cleaning uses the active particles of plasma (such as ions, free radicals, and excited-state atoms or molecules) to chemically react with contaminants on the silicon wafer surface, thereby removing them. This process thoroughly cleans the silicon wafer surface, providing ideal surface conditions for subsequent photolithography, deposition, or etching processes. This comprehensive cleaning approach helps improve the yield and performance of semiconductor devices.
[0094] Step S13: Apply adhesive and photoresist evenly to the cleaned silicon wafer in sequence, and preheat the silicon wafer after applying adhesive and photoresist.
[0095] Specifically, the adhesive's role is to increase the adhesion between the photoresist and the silicon wafer. The adhesive can be uniformly coated onto the silicon wafer surface using methods such as spin coating, spray coating, or dip coating. The adhesive can also fill microscopic defects on the silicon wafer surface, reducing interface defects between the photoresist and the silicon wafer, thereby improving the uniformity and adhesion of the photoresist layer. Photoresist is a key material used for pattern transfer during photolithography. It is also uniformly coated onto the adhesive using methods such as spin coating to form a photoresist layer of a certain thickness. Preheating is performed after photoresist coating to remove solvents from the photoresist and reduce bubbles and stress. Through heating, the solvent in the photoresist evaporates, and the colloidal molecules rearrange to form a denser and more uniform photoresist layer.
[0096] Step S15: Expose and develop the preheated silicon wafer with ultraviolet light, and then harden the developed silicon wafer for a specified duration.
[0097] Specifically, ultraviolet (UV) exposure uses light of a specific wavelength to selectively irradiate a silicon wafer coated with photoresist. During this process, the photosensitizer in the photoresist undergoes a photochemical reaction, causing a change in the chemical composition of the irradiated areas. This allows the photoresist to dissolve in a specific developer during the development process, while the unirradiated areas remain unchanged. The development process uses a developer to treat the exposed photoresist, dissolving it in the exposed areas to reveal the desired pattern. After development, the silicon wafer undergoes a hardening process for a specified duration. The purpose of hardening is to further remove residual solvents from the photoresist, enhance the adhesion between the photoresist and the silicon wafer surface, and improve the photoresist's resistance to subsequent etching and ion implantation processes. The specified duration can be selected as 60 seconds.
[0098] Step S17: Lower the silicon wafer after hardening to a specified temperature to obtain the target silicon wafer after preliminary photolithography.
[0099] Specifically, some solvent may remain in the photoresist. Lowering the temperature to a specified level can promote the evaporation of these residual solvents, thereby reducing pattern defects.
[0100] and Figure 1 Compared to the illustrated embodiment, this embodiment first performs ultrasonic cleaning and plasma cleaning on the silicon wafer to be processed to ensure that the silicon wafer surface is free of contaminants. Next, an adhesive and photoresist are uniformly applied to the cleaned silicon wafer, followed by preheating to improve material adhesion. The preheated silicon wafer undergoes ultraviolet exposure and development to form the desired pattern, followed by a hardening process of a specified duration to optimize the film morphology and uniformity. Finally, the hardened silicon wafer is cooled to a specified temperature to obtain the target silicon wafer after preliminary photolithography. Through effective cleaning, coating, exposure, and processing steps, the efficiency and accuracy of the photolithography process are ensured, ultimately achieving a high-quality photolithography effect.
[0101] Figure 5 The flowchart provided for the embodiments of this application after step S3 may include the following steps:
[0102] Step S5: Compare the pattern size of the target photoresist obtained after cyclic etching with the photoresist to be corrected to determine the size deviation value;
[0103] Step S7: Adjust the mask according to the dimensional deviation value to compensate for the deviation generated during the cyclic etching.
[0104] Please see Figure 6 This is a schematic diagram showing the cross-sectional change of the target silicon wafer after cyclic etching, as provided in an embodiment of this application. Figure 6 As shown, the target silicon wafer 111 has a corrected photoresist 112, a horizontal photoresist surface 113a and a beveled photoresist surface 114a before correction, and a horizontal photoresist surface 113b and a beveled photoresist surface 114b after correction. As can be seen from the figure, due to the consumption of photoresist during cyclic etching, the bevels become steeper, resulting in a dimensional deviation between the final pattern and the actual pattern size on the mask. Taking the bottom surface A as the length of the bottom surface of the photoresist pattern before correction and B as the length of the bottom surface of the photoresist pattern after correction as an example, the dimensional deviation BA is typically between 200-300 nm. Adjusting the mask according to the dimensional deviation can compensate for the deviation generated during cyclic etching. This usually involves changing the size, shape, or layout of the pattern on the mask to optimize pattern transfer during photolithography. Optimized photolithography processes, especially by adjusting the mask and improving etching conditions, can significantly improve the verticality of the photoresist pattern, thereby improving the performance and yield of semiconductor devices.
[0105] The specific implementation of the present invention is described below with reference to a specific application embodiment. This embodiment is achieved through the following steps:
[0106] Step 1001: Silicon Wafer Cleaning. Ultrasonic cleaning with acetone and isopropanol for 5 minutes is performed to remove organic and inorganic contaminants from the silicon wafer surface. After cleaning, the wafer is dried with a nitrogen gun to remove surface moisture. Heating on a hot plate at 120°C for 10-15 minutes further removes moisture. After cooling to room temperature, oxygen plasma cleaning is performed to remove residual organic matter from the surface. Cleaning conditions are: RF power 200W, oxygen flow rate 10 sccm, pressure 10 Pa, and time 5 minutes.
[0107] Step 1002: Spin Coating and Pre-Baking. Before spin coating, apply an adhesive AR300-80 to enhance the adhesion between the photoresist and the silicon wafer. The spin coating parameters are two-stage: the first stage is a spin speed of 800 rpm, an acceleration of 800 rpm / s, and a duration of 5 s; the second stage is a spin speed of 4000 rpm, an acceleration of 3000 rpm / s, and a duration of 60 s. After spin coating, heat on a 100°C hot plate for 60 s to remove solvent and fix the photoresist.
[0108] The photoresist AZ1512 was used for homogenization, with two-stage homogenization parameters: the first stage involved a rotation speed of 500 rpm, an acceleration of 500 rpm / s, and a duration of 5 s; the second stage involved a rotation speed of 4000 rpm, an acceleration of 3000 rpm / s, and a duration of 45 s. After homogenization, the photoresist was heated again at 100℃ for 60 s to ensure uniformity and absence of defects. The homogenization thickness was approximately 1 μm.
[0109] Step 1003: Ultraviolet Exposure. A Suss Micro Tech Lithography MA / BA6 Gen4 double-sided alignment UV lithography system was used. Hard contact mode was employed, with the exposure dose set between 130 and 190 mJ / cm². 2 Ensure the photomask is correctly aligned with the silicon wafer before exposure.
[0110] Step 1004: Development and Hardening. Develop using AZ300-MIF developer for 40 seconds. After development, fix with deionized water for 30 seconds to remove unexposed photoresist areas. Harden the developed silicon wafer on a hot plate at 110°C for 60 seconds to further cure the photoresist. After hardening, cool to room temperature in preparation for subsequent processes.
[0111] Step 1005: Observe the cross-section of the photoresist after development using a scanning electron microscope (SEM). Exposure details are as follows. Figure 7 As shown, Figure 7 This is a schematic diagram showing the cross-sectional views of AZ1512 photoresist after development under different exposure doses. Figure 7In this context, Dose is the exposure dose, Develop Time is the development time, and Profile is the angle of the photoresist bevel.
[0112] Depend on Figure 7 It can be seen that the average angle of the AZ1512 photoresist cross-section is approximately 75° under different exposure doses. The exposure dose is 150 mJ / cm². 2 At that time, the sidewall angle reached the optimal value of 80.8°, but it was still different from the ideal 90° perpendicularity.
[0113] Step 1006: The selected inductively coupled plasma (ICP) etching machine is a PlasmaPro 100Cobra manufactured by Oxford Instruments. A layer of thermally conductive silicone oil is applied to the back of the silicon wafer after photolithography to enhance heat conduction. The silicon wafer coated with thermally conductive silicone oil is placed on a dedicated substrate to ensure its stability during the etching process. The prepared silicon wafer is placed into the reaction chamber of the ICP etching machine. Etching is performed according to the cyclic etching program parameters in Table 1.
[0114] Table 1 Cyclic Etching Program Parameters
[0115]
[0116] Figure 8 This image shows the cross-section of the photoresist after cyclic etching modification, as observed using a scanning electron microscope (SEM). Figure 8 As shown in (a), the modified photoresist morphology exhibits an almost vertical bevel angle of 87.2°. This indicates a significant improvement in sidewall verticality compared to the untreated photoresist. The modified photoresist thickness was measured at 730 nm, meaning that approximately 270 nm of photoresist was consumed during the cyclic etching process. This consumption represents about 30% of the original 1 μm (1000 nm) photoresist thickness, which is acceptable given the process limitations.
[0117] Furthermore, the lateral dimension widening scale is approximately between 200 and 300 nm. This widening scale can be adjusted during mask design to compensate for deviations generated during cyclic etching, ensuring the accuracy of the final pattern.
[0118] Figure 8 As shown in (b) of the image, the SEM image reveals that both the photoresist surface and the surface of the material to be etched are very smooth after the cyclic etching, with no visible signs of damage. This indicates that the etching process is gentle and uniform, without causing unnecessary damage to the material.
[0119] In summary, the etching method for photoresist morphology modification provided in this application can directly achieve steepening of the photoresist bevel through a dry etching process. Compared with traditional multilayer exposure methods, this technology avoids multiple spin coating and photolithography steps, thereby simplifying the entire process flow. This method not only reduces production costs and improves production efficiency but also reduces environmental pollution. Furthermore, this application can flexibly and quickly solve the problem of photoresist bevel angle after development. This cyclic etching method is applicable to various carbon-based photoresists used for ultraviolet exposure, including commonly used models such as the AZ series and SU-8, providing an efficient and environmentally friendly solution for semiconductor manufacturing.
[0120] Accordingly, please refer to Figure 9 A block diagram of an etching apparatus for photoresist morphology modification provided in this application embodiment, the apparatus comprising:
[0121] The silicon wafer acquisition unit S001 is used to acquire a target silicon wafer after preliminary photolithography. The target silicon wafer has photoresist to be corrected, and the surface of the photoresist includes a horizontal plane and a slope.
[0122] The cyclic etching unit S003 is used to perform cyclic etching of photoresist. In one cyclic etching process, there are a deposition stage and a consumption stage. The deposition stage is used to deposit an organic passivation layer on the surface of the photoresist, wherein the amount of organic passivation layer deposited per unit area on the horizontal plane is greater than the amount deposited per unit area on the inclined plane. The consumption stage is used to consume the photoresist in a direction perpendicular to the horizontal plane under the action of the lower electrode RF power supply, and under the action of the organic passivation layer, the amount of photoresist consumed on the inclined plane is greater than the amount of photoresist consumed on the horizontal plane.
[0123] In some alternative embodiments, the apparatus further includes, prior to cyclic etching of the photoresist:
[0124] An initial deposition of an organic passivation layer is performed on the photoresist. The organic passivation layer in the initial deposition process and the organic passivation layer in the cyclic etching process are both obtained by polymerizing carbon difluoride ions ionized by carbon fluoride plasma. A specified amount of oxygen is added to the carbon fluoride plasma during the ionization process.
[0125] Accordingly, the photoresist after initial deposition is cyclically etched.
[0126] In some alternative implementations, the first duration of the initial deposition process is longer than the second duration of the deposition phase during a single etching process, and the first power of the inductively coupled plasma applied during the initial deposition process is higher than the second power of the inductively coupled plasma applied during the deposition phase.
[0127] In some alternative implementations, the lower electrode RF power supply is not turned on during the initial deposition process and during the deposition phase of a single etching process.
[0128] In some alternative implementations, during the initial deposition process, the flow rate of the fluorinated carbon plasma is 35 sccm, the flow rate of oxygen is 8 sccm, the initial deposition process lasts for a first duration of 20 s, the initial power of the inductively coupled plasma applied during the initial deposition process is 500 W, and the pressure in the reaction chamber during the initial deposition process is 20 mTorr.
[0129] In some alternative implementations, during the deposition stage, fluorinated carbon plasma and oxygen are injected into the reaction chamber where the target silicon wafer is located; during the consumption stage, only oxygen is injected into the reaction chamber, and the flow rate of oxygen injected during the consumption stage is higher than that of oxygen injected during the deposition stage.
[0130] In some alternative implementations, the duration of the consumption phase is longer than the duration of the deposition phase, and the power of the inductively coupled plasma applied during the consumption phase is lower than the power of the inductively coupled plasma applied during the deposition phase.
[0131] In some optional embodiments, during the deposition phase, the flow rate of the fluorinated carbon plasma is 35 sccm, the flow rate of oxygen is 8 sccm, the deposition phase lasts for 3 s, and the power of the inductively coupled plasma applied during the deposition phase is 300 W; during the consumption phase, the flow rate of oxygen is 40 sccm, the consumption phase lasts for 5 s, the power of the inductively coupled plasma applied during the consumption phase is 200 W, and the power of the lower electrode radio frequency power supply applied during the consumption phase is 50 W; the pressure in the reaction chamber during both the deposition and consumption phases is 20 mTorr.
[0132] In some alternative implementations, obtaining the target silicon wafer after preliminary photolithography includes:
[0133] For the silicon wafers to be processed, ultrasonic cleaning and plasma cleaning are performed respectively.
[0134] After cleaning, the silicon wafer is coated with adhesive and photoresist in sequence, and then preheated.
[0135] The preheated silicon wafer is subjected to ultraviolet exposure and development, and the developed silicon wafer is then subjected to hardening for a specified duration.
[0136] The silicon wafer after hardening is lowered to a specified temperature to obtain the target silicon wafer after preliminary photolithography.
[0137] Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.
[0138] This application also provides a semiconductor device, which is fabricated based on the above-described etching method for modifying photoresist morphology.
[0139] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by the appended claims.
[0140] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0141] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the apparatus embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.
[0142] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.
[0143] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.
Claims
1. A photoresist morphology modification etching method, characterized in that: The method comprises: Obtaining a target silicon wafer after preliminary photolithography, the target silicon wafer having a photoresist to be corrected, wherein the surface of the photoresist includes a horizontal surface and an inclined surface; The photoresist is subjected to cyclic etching; during one etching process of the cyclic etching, a deposition phase and a consumption phase are included; the deposition phase is used to deposit an organic passivation layer on the surface of the photoresist, wherein the amount of the organic passivation layer deposited per unit area on the horizontal plane is greater than the amount deposited per unit area on the inclined plane; the consumption phase is used to consume the photoresist in a direction perpendicular to the horizontal plane under the action of a lower electrode radio frequency power supply, and under the action of the organic passivation layer, the amount of photoresist consumed on the inclined plane is greater than the amount of photoresist consumed on the horizontal plane.
2. The method according to claim 1, characterized in that Before cyclically etching the photoresist, the method further comprises: Performing initial deposition of an organic passivation layer on the photoresist, wherein the organic passivation layer in the initial deposition process and the organic passivation layer in the cyclic etching process are both obtained by polymerization of carbon difluoride ions ionized by carbon fluoride plasma, and a specified amount of oxygen is added to the carbon fluoride plasma during the ionization process; Accordingly, the photoresist after the initial deposition is cyclically etched.
3. The method according to claim 2, characterized in that The first duration of the initial deposition process is longer than the second duration of the deposition phase in the primary etching process, and the first power of the inductively coupled plasma applied during the initial deposition process is higher than the second power of the inductively coupled plasma applied during the deposition phase.
4. The method according to claim 2 or 3, characterized in that: During the initial deposition process and the deposition phase of the first etching process, the lower electrode radio frequency power supply is not turned on.
5. The method according to claim 2, characterized in that: During the initial deposition process, the flow rate of the carbon fluoride plasma is 35 sccm, the flow rate of the oxygen is 8 sccm, the first duration of the initial deposition process is 20 s, the first power of the inductively coupled plasma applied during the initial deposition process is 500 W, and the pressure in the reaction chamber during the initial deposition process is 20 mTorr.
6. The method according to claim 1, characterized in that In the deposition phase, carbon fluoride plasma and oxygen are injected into the reaction chamber where the target silicon wafer is located; in the consumption phase, only oxygen is injected into the reaction chamber, and the flow rate of the oxygen injected in the consumption phase is higher than the flow rate of the oxygen injected in the deposition phase.
7. The method according to claim 1 or 6, characterized in that: The duration of the consumption phase is longer than the duration of the deposition phase, and the power of the inductively coupled plasma applied during the consumption phase is lower than the power of the inductively coupled plasma applied during the deposition phase.
8. The method according to claim 6, characterized in that In the deposition stage, the flow rate of the carbon fluoride plasma is 35 sccm, the flow rate of the oxygen is 8 sccm, the deposition stage lasts for 3 s, and the power of the inductively coupled plasma applied in the deposition stage is 300 W; in the consumption stage, the flow rate of the oxygen is 40 sccm, the consumption stage lasts for 5 s, the power of the inductively coupled plasma applied in the consumption stage is 200 W, and the power of the lower electrode RF power supply applied in the consumption stage is 50 W; the pressure in the reaction chamber in both the deposition stage and the consumption stage is 20 mTorr.
9. The method according to claim 1, characterized in that: Obtaining the target silicon wafer after preliminary lithography includes: For the silicon wafer to be processed, ultrasonic cleaning and plasma cleaning are performed on the silicon wafer to be processed respectively; The cleaned silicon wafer is coated with adhesive and photoresist in sequence, and the silicon wafer coated with adhesive and photoresist is preheated; The pre-heated silicon wafer is subjected to UV exposure and development, and the developed silicon wafer is hardened for a specified period of time; The hardened silicon wafer is lowered to a specified temperature to obtain the target silicon wafer after preliminary photolithography.
10. An etching device for photoresist morphology modification, characterized in that: The device comprises: A silicon wafer acquisition unit, used for acquiring a target silicon wafer after preliminary photolithography, wherein the target silicon wafer has a photoresist to be corrected, and the surface of the photoresist includes a horizontal surface and an inclined surface; A cyclic etching unit is used to perform cyclic etching on the photoresist; during one etching process of the cyclic etching, it includes a deposition stage and a consumption stage; the deposition stage is used to deposit an organic passivation layer on the surface of the photoresist, wherein the amount of the organic passivation layer deposited per unit area on the horizontal plane is greater than the amount deposited per unit area on the inclined plane; the consumption stage is used to consume the photoresist in a direction perpendicular to the horizontal plane under the action of a lower electrode radio frequency power supply, and under the action of the organic passivation layer, the amount of photoresist consumed on the inclined plane is greater than the amount of photoresist consumed on the horizontal plane.
11. A semiconductor device, characterized in that: The semiconductor device is manufactured based on the etching method for modifying the photoresist morphology as described in any one of claims 1 to 9.