Manufacturing method of comb tooth structure and groove structure
By regulating the flow ratio of passivation gas and etching gas, the smoothness and steepness of the sidewall of the trench structure are optimized during the etching process, and the problems of unsmooth and inclination of the sidewall of the high-deep aspect ratio groove in the prior art are solved, and the performance of comb-tooth structure devices are improved.
Patent Information
- Application Number
- CN202311848567.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-28
- Publication Date
- 2025-07-04
AI Technical Summary
The smoothness of the side walls of the trench structure formed by the existing Bosch etching process is poor, and the side walls of the trench structure formed by the pseudo-Bosch etching process have an inclination, which affects the performance of the comb-tooth structure devices.
During the etching process, the passivation gas flow rate is gradually reduced and the etching gas flow rate is gradually increased, the ratio of passivation and etching gas is adjusted, the etching effect is optimized, and the side walls of the trench are smooth and steep.
The side walls of the high-deep aspect ratio groove are smooth and steep, which improves the breakdown voltage of the comb-tooth structure device, reduces the capacitance and improves device performance.
Smart Images
Figure CN120261283A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of semiconductor integrated circuit manufacturing, and relates to a manufacturing method for a comb structure and a trench structure. Background Art
[0002] In semiconductor etching processes, especially in structures with a high aspect ratio, there have always been certain problems in reducing the roughness of the etched sidewalls. This is especially true for common comb structures. A comb structure with smooth trench sidewalls may have a higher breakdown voltage and form a higher capacitance in functional applications. Etching a trench structure with a high aspect ratio generally uses the Bosch process.
[0003] During the etching process using the Bosch process, the "etching - passivation - etching" method is usually used to etch the trench. For example, setting the flow rate of the passivation gas perfluorocyclobutane to 400 standard milliliters per minute and the flow rate of the etching gas sulfur hexafluoride to 600 standard milliliters per minute, the "passivation" and "etching" processes are cycled. The cross-section after etching is as Figure 1 shown, including a semiconductor structure 01 and a trench 011. Although this etching method achieves a high aspect ratio, the sidewalls of the trenches in the comb structure show "scallop" patterns, resulting in insufficient smoothness, which will affect the performance of devices using the comb structure. Of course, the "passivation" and "etching" can also be carried out simultaneously for trench etching, commonly known as the "pseudo - Bosch process". For example, setting the flow rate of the passivation gas perfluorocyclobutane to 400 standard milliliters per minute and the flow rate of the etching gas sulfur hexafluoride to 600 standard milliliters per minute, the "passivation" and "etching" processes are carried out simultaneously. The cross-section after etching is as Figure 2 shown, including a semiconductor structure 01 and a trench 011. Although this etching method achieves smooth sidewalls and a high aspect ratio for the trench, the sidewalls of the trench have a relatively serious inclination angle, which still affects the performance of devices using the comb structure.
[0004] Therefore, there is an urgent need to find a manufacturing method for a trench structure that can improve the straightness and smoothness of the sidewalls of trenches formed by the Bosch etching process. Summary of the Invention
[0005] In view of the above - mentioned disadvantages of the prior art, the purpose of the present invention is to provide a manufacturing method for a comb structure and a trench structure, which is used to solve the problems of poor smoothness of the sidewalls of the trench structure with a high aspect ratio formed by the Bosch etching process in the prior art and the inclination angle of the trench structure formed by the pseudo - Bosch etching process.
[0006] To achieve the above - mentioned purpose and other related purposes, the present invention provides a manufacturing method for a trench structure, including the following steps:
[0007] Provide a semiconductor structure, and form a patterned masking layer covering the upper surface of the semiconductor structure on the upper surface of the semiconductor structure;
[0008] Place the semiconductor structure with the patterned masking layer formed on its upper surface in an etching process chamber of an etching device;
[0009] Synchronously introduce a first preset flow rate of a passivation gas and a second preset flow rate of an etching gas into the etching process chamber, and at the same time etch the semiconductor structure based on the patterned masking layer to obtain a trench. During the process of etching the semiconductor structure, gradually reduce the flow rate of the passivation gas and gradually increase the flow rate of the etching gas. When the etching ends, the flow rate of the passivation gas is reduced to a third preset flow rate, and the flow rate of the etching gas is increased to a fourth preset flow rate.
[0010] Optionally, the material of the masking layer includes silicon oxide, silicon nitride, silicon oxynitride, amorphous carbon, and photoresist.
[0011] Optionally, the components of the passivation gas include perfluorocyclobutane; the components of the etching gas include sulfur hexafluoride.
[0012] Optionally, the way of gradually reducing the passivation gas includes gradually decreasing.
[0013] Optionally, the way of gradually increasing the etching gas includes gradually increasing.
[0014] Optionally, the ratio of the depth of the trench to the width of the trench opening is not less than 10:1.
[0015] Optionally, the range of the angle between the side wall of the trench and the bottom surface of the trench is 85° to 95°.
[0016] Optionally, after forming the trench, it further includes the step of removing the masking layer covering the upper surface of the semiconductor structure.
[0017] The present invention also provides a comb structure, and the trenches in the comb structure are made by using the manufacturing method of the trench structure described above.
[0018] Optionally, the trenches in the comb structure include a first part and a second part with openings extending along the X direction and bending back and forth at least once in the Y direction. One end of the first part is communicated with one end of the second part and is symmetric about a straight line parallel to the X direction.
[0019] As described above, the method for manufacturing the comb tooth structure and the trench structure of the present invention improves the process for manufacturing the trench. After forming the patterned masking layer and etching the semiconductor structure based on the patterned masking layer, by adjusting the flow rates of the passivation gas and the etching gas during the etching process, the flow rate of the passivation gas gradually decreases and the flow rate of the etching gas gradually increases during the formation of the trench. Consequently, during the formation of the trench, the passivation effect gradually weakens and the etching effect gradually strengthens, optimizing the passivation effect and the etching effect during the etching process. This makes the sidewalls of the obtained trench with a high aspect ratio smooth and steep, avoiding the inclination of the sidewalls of the trench or the formation of "scallop" patterns. Moreover, by using the method for manufacturing the trench structure to manufacture the trench in the comb tooth structure, the trench in the comb tooth structure can have a high aspect ratio while the sidewalls of the trench are smooth and steep, improving the morphology of the trench in the comb tooth structure, enhancing the breakdown voltage of the device applying the comb tooth structure, reducing the capacitance of the device, and then improving the performance of the device, which has high industrial utilization value. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 FIG. shows a schematic cross-sectional structure diagram of a comb tooth structure.
[0021] Figure 2 FIG. shows another schematic cross-sectional structure diagram of a comb tooth structure.
[0022] Figure 3 FIG. shows a process flow chart of the method for manufacturing the trench structure of the present invention.
[0023] Figure 4 FIG. shows a schematic top view structure diagram of the comb tooth structure of the present invention.
[0024] Figure 5 FIG. shows a schematic cross-sectional structure diagram of the comb tooth structure of the present invention.
[0025] DESCRIPTION OF THE REFERENCE NUMERALS IN THE DRAWINGS
[0026] 01 Semiconductor structure
[0027] 011 Trench
[0028] 1 Semiconductor structure
[0029] 11 Trench
[0030] 111 First part
[0031] 112 Second part DETAILED DESCRIPTION OF THE INVENTION
[0032] The following describes the implementation manners of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0033] Please refer to Figures 3 to 5 . It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.
[0034] Embodiment 1
[0035] This embodiment provides a method for fabricating a trench structure. As Figure 3 shown, it is a process flow diagram of the method for fabricating the trench structure, including the following steps:
[0036] S1: Provide a semiconductor structure, and form a patterned masking layer covering the upper surface of the semiconductor structure on the upper surface of the semiconductor structure;
[0037] S2: Place the semiconductor structure with the patterned masking layer formed on its upper surface in the etching process chamber of an etching device;
[0038] S3: Synchronously introduce a first preset flow rate of a passivation gas and a second preset flow rate of an etching gas into the etching process chamber, and simultaneously etch the trench based on the patterned masking layer. During the formation of the trench, gradually reduce the flow rate of the passivation gas and gradually increase the flow rate of the etching gas. When the trench structure is formed after the etching is completed, the flow rate of the passivation gas is reduced to a third preset flow rate, and the flow rate of the etching gas is increased to a fourth preset flow rate.
[0039] Specifically, perform step S1 and step S2: Provide a semiconductor structure 1, and form a patterned masking layer 2 covering the upper surface of the semiconductor structure 1 on the upper surface of the semiconductor structure 1; Place the semiconductor structure 1 with the patterned masking layer 2 formed on its upper surface in the etching process chamber of an etching device.
[0040] Specifically, the semiconductor structure includes one of a single-layer film and a multi-layer film.
[0041] Specifically, when the semiconductor structure includes a single-layer film layer, the material of the semiconductor structure includes silicon, silicon germanium, silicon carbide, or other suitable semiconductor materials; the thickness, size, and shape of the semiconductor structure can be selected according to actual situations and are not limited here.
[0042] Specifically, when the semiconductor structure is a multi-layer film layer structure, only the top layer film of the semiconductor structure is etched during subsequent etching of the semiconductor structure. Under the condition of ensuring the performance of the subsequent fabricated device, the thickness and shape of each film layer in the semiconductor structure can be selected according to actual situations and are not limited here.
[0043] As an example, the material of the masking layer includes silicon oxide, silicon nitride, silicon oxynitride, amorphous carbon, photoresist, or other suitable materials.
[0044] Specifically, the masking layer includes one of a single-layer film layer structure and a multi-layer film layer structure. For example, the masking layer can be a single-layer hard mask layer or a multi-layer hard mask layer, or a composite film layer structure of a multi-layer film layer composed of a hard mask layer and a photoresist layer.
[0045] Specifically, the method of patterning the masking layer is a commonly used photolithography process and will not be elaborated here.
[0046] Specifically, under the condition of ensuring the morphology of the subsequent formed trench, the thickness of the masking layer can be selected according to actual situations and is not limited here.
[0047] Specifically, the etching equipment is a commonly used equipment for Bosch process, and its structure and types will not be elaborated here.
[0048] Specifically, the method of placing the semiconductor structure in the etching process chamber of the etching equipment is a commonly used semiconductor structure transfer method and will not be elaborated here, nor will the size and structure of the etching process chamber be elaborated.
[0049] Specifically, perform step S3: synchronously introduce a first preset flow rate of passivation gas and a second preset flow rate of etching gas into the etching process chamber, and at the same time etch the semiconductor structure based on the patterned masking layer to obtain a trench. During the process of etching the semiconductor structure, gradually reduce the flow rate of the passivation gas and gradually increase the flow rate of the etching gas. When the etching is completed to form a trench structure, the flow rate of the passivation gas is reduced to a third preset flow rate, and the flow rate of the etching gas is increased to a fourth preset flow rate.
[0050] As an example, the components of the passivation gas include perfluorocyclobutane or other gases with passivation effects suitable for Bosch etching processes; the components of the etching gas include sulfur hexafluoride or other gases with etching effects suitable for Bosch etching processes. In this embodiment, perfluorocyclobutane is used as the passivation gas and sulfur hexafluoride is used as the etching gas.
[0051] Specifically, the passivation gas is used to passivate the exposed sidewalls of the trenches formed during the etching of the semiconductor structure, forming a passivation layer that shields the exposed sidewalls of the trenches, and using the shielding of the passivation layer to prevent the semiconductor structure on the sidewalls of the trenches from contacting the etching gas, thereby avoiding the etching gas from etching the sidewalls of the trenches; the etching gas is used to etch the exposed surface of the semiconductor structure.
[0052] Specifically, under the condition of ensuring the morphology and aspect ratio of the formed trenches, the flow rate value of the first preset flow rate can be selected according to the actual situation and will not be limited here; the flow rate value of the second preset flow rate can be selected according to the actual situation and will not be limited here. In this embodiment, the first preset flow rate of the passivation gas introduced into the etching process chamber is 400 sccm, and the second preset flow rate of the etching gas introduced into the etching process chamber is 600 sccm.
[0053] Specifically, the first preset flow rate of the passivation gas and the second preset flow rate of the etching gas are synchronously introduced into the etching process chamber, so that during the process of etching the semiconductor structure to form the trenches, the passivation of the sidewalls of the trenches and the etching of the bottom of the trenches are carried out simultaneously.
[0054] As an example, the way to gradually reduce the passivation gas includes gradually decreasing. For example, the variation curve of the flow rate of the passivation gas during the entire etching process can be monotonically decreasing or stepwise decreasing.
[0055] As an example, the way to gradually increase the etching gas includes gradually increasing. For example, the variation curve of the flow rate of the etching gas during the entire etching process can be monotonically increasing or stepwise increasing.
[0056] As an example, the ratio of the depth of the trench to the width of the trench opening is not less than 10:1, that is, the trench is a trench with a high aspect ratio.
[0057] Specifically, under the condition of ensuring the performance of the subsequent formed device, the opening size of the trench can be selected according to the actual situation and will not be limited here.
[0058] Specifically, in the case of actual device requirements, the opening shape of the trench can be selected according to the actual situation, which will not be elaborated here.
[0059] As an example, the range of the angle between the side wall of the trench and the bottom surface of the trench is 85° to 95°.
[0060] Specifically, since the passivation gas decreases in a decreasing manner during the entire etching process and the etching gas increases in an increasing manner during the entire etching process, during the process of etching the semiconductor structure, the passivation effect gradually weakens and the etching effect gradually strengthens. Subsequently, during the process of forming the trench, the passivation and etching processes are optimized synchronously, enabling the trench to have a smooth side wall and a high aspect ratio, and the side wall of the trench will not be inclined, making the side wall of the trench steeper.
[0061] Specifically, the strength of the passivation effect of the passivation gas on the exposed surface of the semiconductor structure is related to the flow rate of the passivation gas, the concentration of the effective component, the material of the semiconductor structure, and the etching temperature. The strength of the etching effect of the etching gas on the exposed surface of the semiconductor structure is related to the concentration of the effective component, the flow rate, the material of the semiconductor structure, and the etching temperature. Under the condition of ensuring the morphology of the formed trench, the flow rate value of the third preset flow rate can be selected according to the actual situation, which is not limited here; the flow rate value of the fourth preset flow rate can be selected according to the actual situation, which is not limited here. In this embodiment, at the end of etching, the flow rate value of the third preset flow rate is 300 sccm, and the flow rate value of the fourth preset flow rate is 800 sccm.
[0062] As an example, after forming the trench, it further includes the step of removing the masking layer covering the upper surface of the semiconductor structure.
[0063] Specifically, the method for removing the masking layer includes dry etching, wet etching, or other suitable methods.
[0064] Specifically, during the process of etching the semiconductor structure based on the patterned masking layer, the first preset flow rate of the passivation gas and the second preset flow rate of the etching gas are simultaneously introduced into the etching process chamber, realizing simultaneous etching and passivation. Moreover, the flow rate of the passivation gas gradually decreases from the start to the end of etching, and the flow rate of the etching gas gradually increases from the start to the end of etching. In this way, during the process of forming the trench, the passivation effect of the passivation gas gradually weakens, and the etching effect of the etching gas gradually strengthens, optimizing the passivation effect and etching effect during the entire etching process, enabling the formed trench to have a high aspect ratio while the side wall of the trench is smooth and steep, and avoiding the inclination of the side wall of the trench or the formation of "scallop" patterns.
[0065] The manufacturing method of the trench structure in this embodiment improves the process of manufacturing the trench. After forming the patterned masking layer, when etching the semiconductor structure based on the patterned masking layer, by adjusting the flow rates of the passivation gas and the etching gas, the flow rate of the passivation gas gradually decreases, and the flow rate of the etching gas gradually increases. Subsequently, during the process of etching the semiconductor structure to form the trench, the passivation effect gradually weakens, and the etching effect gradually strengthens, optimizing the passivation effect and the etching effect during the etching process, making the sidewalls of the obtained trench with a high aspect ratio smooth and steep, and avoiding the problems of the sidewalls of the trench being inclined or forming "scallop" patterns.
[0066] Embodiment Two
[0067] This embodiment provides a comb structure, as Figure 4 and Figure 5 shown, which are respectively the top view structure diagram and the cross-sectional structure diagram of the comb structure. The trench in the comb structure is manufactured by using the manufacturing method of the trench structure in Embodiment One.
[0068] As an example, the trench 11 in the comb structure includes a first part 111 and a second part 112 whose openings extend along the X direction and bend back and forth at least once in the Y direction ( Figure 4 the dashed part in), one end of the first part 111 is communicated with one end of the second part 112 and is symmetric about a straight line parallel to the X direction. That is, both the first part 111 and the second part 112 extend along the X direction, and at the same time, both the first part 111 and the second part 112 bend back and forth at least once in the Y direction, and the number of times the first part 111 and the second part 112 bend back and forth in the Y direction is the same and forms a symmetric structure.
[0069] Specifically, when needed based on the manufactured device, the first part 111 and the second part 112 in the comb structure may also be asymmetrically distributed.
[0070] Specifically, when the trench 11 is embedded in the semiconductor structure 1 and the first part 111 and the second part 112 are symmetrically distributed, when needed based on the actual device, the number of times the first part 111 and the second part 112 bend back and forth in the Y direction can be selected according to the actual situation, which will not be elaborated here.
[0071] Specifically, by using the manufacturing method of the trench structure in Embodiment One to manufacture the trench 11 in the comb structure, the trench 11 can have an aspect ratio of not less than 10:1.
[0072] Specifically, by using the manufacturing method of the groove structure described in the first embodiment to manufacture the comb structure, the side walls of the grooves 11 in the comb structure are made steeper and smoother, improving the morphology of the grooves 11 in the comb structure, avoiding the problems of low breakdown voltage and high capacitance of the device applying the comb structure, and improving the performance of the device applying the comb structure.
[0073] The grooves 11 in the comb structure of this embodiment are manufactured by using the manufacturing method of the groove structure described in the first embodiment. While making the grooves 11 have a high aspect ratio, the side walls of the grooves 11 are made smooth and steeper, improving the morphology of the grooves 11, increasing the breakdown voltage of the device applying the comb structure, reducing the capacitance of the device applying the comb structure, and then improving the performance of the device applying the comb structure.
[0074] In summary, the manufacturing method of the comb structure and the groove structure of the present invention improves the process of manufacturing grooves. When etching a semiconductor structure based on a patterned masking layer, by adjusting the flow rates of the passivation gas and the etching gas, the flow rate of the passivation gas gradually decreases and the flow rate of the etching gas gradually increases. Then, during the process of forming the grooves, the passivation effect gradually weakens and the etching effect gradually strengthens, optimizing the passivation effect and the etching effect during the etching process. While obtaining grooves with a high aspect ratio, the side walls of the grooves become smooth and steep, avoiding problems such as the inclination of the side walls of the grooves or the formation of "scallop" patterns. Moreover, by using the manufacturing method of the groove structure to manufacture the grooves in the comb structure, the grooves in the comb structure can have a high aspect ratio and smooth and steep side walls, improving the morphology of the grooves in the comb structure, increasing the breakdown voltage of the device applying the comb structure, reducing the capacitance of the device applying the comb structure, and then improving the performance of the device applying the comb structure. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.
[0075] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.
Claims
1. A manufacturing method of a trench structure, characterized in that Comprising the following steps: Providing a semiconductor structure, and forming a patterned masking layer covering the upper surface of the semiconductor structure on the upper surface of the semiconductor structure; Placing the semiconductor structure with the patterned masking layer formed on the upper surface into an etching process chamber of an etching device; Simultaneously introducing a first preset flow rate of a passivation gas and a second preset flow rate of an etching gas into the etching process chamber, and at the same time etching the semiconductor structure based on the patterned masking layer to obtain a trench, and during the process of etching the semiconductor structure, gradually reducing the flow rate of the passivation gas and gradually increasing the flow rate of the etching gas. When the etching ends, the flow rate of the passivation gas is reduced to a third preset flow rate, and the flow rate of the etching gas is increased to a fourth preset flow rate.
2. The manufacturing method of the trench structure according to claim 1, characterized in that: The material of the masking layer includes silicon oxide, silicon nitride, silicon oxynitride, amorphous carbon, and photoresist.
3. The manufacturing method of the trench structure according to claim 1, characterized in that: The components of the passivation gas include perfluorocyclobutane; the components of the etching gas include sulfur hexafluoride.
4. The manufacturing method of the trench structure according to claim 1, wherein: The way of gradually reducing the passivation gas includes gradually decreasing.
5. The manufacturing method of the trench structure according to claim 1, characterized in that: The way of gradually increasing the etching gas includes gradually increasing.
6. The manufacturing method of the trench structure according to claim 1, characterized in that: The ratio between the depth and the opening width of the trench is not less than 10:
1.
7. The manufacturing method of the trench structure according to claim 1, characterized in that: The range of the angle between the side wall and the bottom surface of the trench is 85° to 95°.
8. The manufacturing method of the trench structure according to claim 1, characterized in that: After forming the trench, it further includes the step of removing the masking layer covering the upper surface of the semiconductor structure.
9. A comb tooth structure, characterized in that, The trench in the comb structure is fabricated by using the manufacturing method of the trench structure according to any one of claims 1 to 8.
10. The comb tooth structure according to claim 9, wherein: The trench in the comb structure includes a first part and a second part with openings extending along the X direction and bending back and forth at least once in the Y direction. One end of the first part is communicated with one end of the second part and is symmetric about a straight line parallel to the X direction.