Method for forming trench, manufacturing method for semiconductor device, and process apparatus

Abstract

The present disclosure provides a method for forming a trench, a manufacturing method for a semiconductor device, and a process apparatus. The method for forming a trench is applied to a film layer to be etched, a mask layer being provided on said film layer; the mask layer has a first opening and a second opening, the opening size of the first opening being greater than the opening size of the second opening; the first opening exposes a first region of said film layer, and the second opening exposes a second region of said film layer; the method comprises: performing a first etching step of using a main etching gas to etch the first region and the second region so as to remove said film layer in the first region and part of said film layer in the second region; and performing a second etching step of using the main etching gas and a first sidewall protection gas to etch said film layer exposed in the second region, so as to form a trench, wherein, during the etching process, the first sidewall protection gas is used for reacting with said film layer remaining in the second region, so as to generate a first by-product, thus preventing the sidewall of the trench from being laterally etched. The present solution can be used to effectively improve the etching efficiency.

Description

Methods for forming trenches, methods for fabricating semiconductor devices, and process equipment. Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a method for forming trenches, a method for fabricating semiconductor devices, and process equipment. Background Technology

[0002] In the manufacturing process of semiconductor devices, metal gates are needed to interconnect the semiconductor devices. Related techniques typically employ a single-step etching process to etch the film to be etched, forming the metal gates and trenches that isolate adjacent metal gates. In this single-step etching process, a first sidewall protection gas is usually added. This gas reacts with the film to be etched to generate a first byproduct, which is deposited on the sidewalls of the trench to protect them. However, when the film to be etched has regions with different opening sizes, this single-step etching method has extremely low etching efficiency, reducing the efficiency of trench fabrication. Summary of the Invention

[0003] This application provides a method for forming trenches, a method for fabricating semiconductor devices, and process equipment to solve the problem in related technologies where the etching efficiency is extremely low due to the addition of a first sidewall protective gas in a single etching step, thereby reducing the fabrication efficiency of trenches.

[0004] The first aspect of this application provides a method for forming a trench, applied to a film layer to be etched. A mask layer is disposed on the film layer to be etched, the mask layer having a first opening and a second opening. The opening size of the first opening is larger than the opening size of the second opening. The first opening exposes a first region of the film layer to be etched, and the second opening exposes a second region of the film layer to be etched. The method includes: performing a first etching step, using a main etching gas to etch the first region and the second region to remove the film layer to be etched in the first region and a portion of the film layer to be etched in the second region; performing a second etching step, using the main etching gas and a first sidewall protection gas to etch the film layer to be etched exposed in the second region to form a trench. The first sidewall protection gas is used to react with the film layer to be etched in the second region during the etching process to generate a first byproduct, so as to prevent the sidewalls of the trench from being laterally etched.

[0005] In one embodiment, performing the first etching step includes: when the first etching step is started, monitoring the spectral intensity of the feature product of the film to be etched; when the spectral intensity of the feature product of the film to be etched decreases to a preset multiple of the spectral intensity reference value, stopping the first etching step; wherein the spectral intensity reference value is the value when the spectral intensity of the feature product enters a stable state, the preset multiple is a decimal greater than 0 and less than 1, and the preset multiple has an inverse proportional relationship with the aperture ratio of the first opening.

[0006] In one embodiment, performing the second etching step includes: during the second etching step, monitoring the spectral intensity of the characteristic products of the film to be etched; and stopping the second etching step when the spectral intensity of the characteristic products of the film to be etched decreases continuously for a preset number of times; the preset number of times is an integer greater than or equal to 2.

[0007] In one embodiment, in the first etching step, the main etching gas reacts with the film layer to be etched in the first region and a portion of the film layer to be etched in the second region to generate a second byproduct; in the second etching step, the main etching gas reacts with the remaining film layer to be etched in the second region to generate a third byproduct; wherein the amount of the third byproduct generated is less than the amount of the second byproduct generated.

[0008] In one embodiment, during the execution of the first etching step and the second etching step, the second sidewall protective gas is also used to react with the sidewall of the trench to generate a fourth byproduct. The fourth byproduct has a weaker protective ability on the bottom of the sidewall of the trench than on the top of the sidewall of the trench. The first byproduct is also used to compensate for the sidewall protection ability of the fourth byproduct on the bottom of the sidewall of the trench.

[0009] In one embodiment, the film to be etched comprises aluminum, the first sidewall protective gas comprises a hydrocarbon gas, and the second sidewall protective gas comprises a nitrogen-containing gas.

[0010] In one embodiment, a first barrier layer is disposed on the side of the film layer to be etched away from the mask layer, and a second barrier layer is disposed between the film layer to be etched and the mask layer. The method further includes at least one of the following: performing a second barrier layer etching step before performing a first etching step to expose a first region of the film layer to be etched and a second region of the film layer to be etched; and performing a first barrier layer etching step after performing a second etching step to make the trench penetrate the first barrier layer.

[0011] In one embodiment, the film layer to be etched has a sparse pattern region and a dense pattern region, with a first region of the film layer to be etched located in the sparse pattern region and a second region of the film layer to be etched located in the dense pattern region.

[0012] A second aspect of this application provides a method for fabricating a semiconductor device, comprising: forming a plurality of semiconductor devices, wherein the plurality of semiconductor devices are interconnected by a film layer to be etched; the film layer to be etched includes a first region and a second region; forming a trench in the second region of the film layer to be etched using a trench forming method according to any of the above embodiments, so as to cut off the film layer to be etched, thereby forming a plurality of metal gates in the film layer to be etched.

[0013] A third aspect of this application provides a semiconductor process apparatus, comprising: a process chamber, an inlet assembly, an upper electrode assembly, a lower electrode assembly, and a controller. The controller includes at least one processor and at least one memory, the memory storing a computer program, which, when executed by the processor, implements the method of any of the above embodiments.

[0014] The advantages or beneficial effects of the above technical solution include at least the following: In the first etching step, when the main etching gas simultaneously etches the film layer to be etched in the first region and part of the film layer to be etched in the second region, since both the first and second regions of the film layer to be etched are exposed, the exposed area of ​​the film layer to be etched is large. The main etching gas reacts with the film layer to be etched and generates more etching by-products. These etching by-products are deposited on the top of the sidewall of the trench, which can play a sidewall protection role, eliminating the need to add an additional first sidewall protection gas. This avoids the first sidewall protection gas hindering etching and is beneficial to improving etching efficiency. High etching efficiency; In the second etching step, since the film to be etched in the first region has been completely etched, only the remaining film to be etched in the second region needs to be etched. At this point, only the second region of the film to be etched is exposed, reducing the exposed area of ​​the film. This reduces the etching byproducts generated by the reaction of the main etching gas with the film. The first byproduct generated by the reaction of the first sidewall protection gas with the remaining film in the second region can then co-deposit with the smaller amount of etching byproducts at the bottom of the trench sidewall, providing sidewall protection and preventing lateral etching of the trench sidewall bottom. Based on this, this method can effectively improve etching efficiency while ensuring a good sidewall morphology in the trench, thereby improving the trench fabrication efficiency. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Furthermore, these drawings and textual descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art by reference to specific embodiments.

[0016] Figures 1A to 1C show a cross-sectional structural schematic diagram of the trench formation process in related technologies.

[0017] Figure 1D shows a cross-sectional structural diagram of an alternative to Figure 1C.

[0018] Figure 2 is a flowchart illustrating a method for forming a trench according to an embodiment of this application.

[0019] Figures 3A to 3D show a cross-sectional structural schematic diagram of a trench formation process according to an embodiment of this application.

[0020] Figure 4 shows a schematic diagram of the etching endpoint capture in the first etching step.

[0021] Figure 5 shows a schematic diagram of the etching endpoint capture in the second etching step.

[0022] Figure 6 shows a schematic diagram of the structure of a semiconductor process apparatus according to an embodiment of this application. Detailed Implementation

[0023] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0024] As shown in Figures 1A to 1C, in related technologies, a mask layer 15 is provided on the film layer 13 to be etched. The mask layer 15 has a first opening 15A and a second opening 15B. The opening size of the first opening 15A is larger than the opening size of the second opening 15B. The first opening 15A exposes a first region 131 of the film layer 13 to be etched, and the second opening 15B exposes a portion of a second region 132 of the film layer 13 to be etched. Related technologies typically employ a single-step etching process to etch the film layer 13, and a first sidewall protection gas, such as trifluoromethane (CHF3), is added during the etching process. The first sidewall protection gas reacts with the first region 13A and the second region 13B of the film layer 13 to generate a first byproduct, which is deposited on the sidewall of the trench 132A to protect the sidewall of the trench 132A.

[0025] During the implementation of this application, the inventors discovered that, as shown in Figures 1A and 1B, because the opening size of the first opening 15A of the mask layer 15 is larger than the opening size of the second opening 15B, the etching rate of the main etching gas on the film layer 13 to be etched in the first region 131 is faster than the etching rate on the film layer 13 to be etched in the second region 132. Therefore, in the single-step etching step, the main etching gas first simultaneously etches the film layer 13 to be etched in the first region 131 and part of the film layer 13 to be etched in the second region 132, generating more etching byproducts. Then, etching the remaining film layer 13 to be etched in the second region 132 generates fewer etching byproducts. The larger amount of etching byproducts can be etched... During the etching process, the top 1321 of the sidewall of trench 132A is effectively protected, which causes the added first sidewall protective gas to hinder the etching. For example, during the simultaneous etching of the film layer 13 to be etched in the first region 131 and part of the film layer 13 to be etched in the second region 132, the first byproduct generated by the reaction between the first sidewall protective gas and the film layer 13 to be etched in the first region 131 and part of the film layer 13 to be etched in the second region 132 will be deposited at the bottom of trench 132A. This means that the main etching gas needs to first etch away the first byproduct at the bottom of trench 132A before it can continue to etch downwards, resulting in extremely low etching efficiency of the single-step etching step and reducing the fabrication efficiency of trench 132A.

[0026] In view of this, embodiments of this application provide a method for forming trenches, a method for fabricating semiconductor devices, and process equipment, which can effectively solve the problem in related technologies where the etching efficiency is extremely low due to the addition of a first sidewall protective gas in a single etching step, thereby reducing the fabrication efficiency of trenches. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0027] Figure 2 is a flowchart illustrating a method for forming a trench according to an embodiment of this application.

[0028] Referring to Figures 2 and 3A, this trench formation method can be applied to a film layer 13 to be etched. A mask layer 15 is disposed on the film layer 13, and the mask layer 15 has a first opening 15A and a second opening 15B. The opening size of the first opening 15A is larger than the opening size of the second opening 15B. The first opening 15A exposes a first region 131 of the film layer 13 to be etched, and the second opening 15B exposes at least a portion of a second region 132 of the film layer 13 to be etched. The opening size of the first opening 15A can be the opening width D1, and the opening size of the second opening 15B can be the opening width D2.

[0029] Please refer to Figures 2, 3A to 3C. The method for forming the trench includes the following steps S110 to S120.

[0030] Step S110: Perform the first etching step, using the main etching gas to etch the first region 131 and the second region 132 of the film layer 13 to be etched, so as to remove the film layer 13 to be etched in the first region 131 and part of the film layer 13 to be etched in the second region 132.

[0031] For example, in step S110, since the first region 131 and the second region 132 of the film layer 13 to be etched are exposed simultaneously, the exposed area of ​​the film layer 13 to be etched is relatively large. Etching the film layer 13 to be etched in the first region 131 and part of the film layer 13 to be etched in the second region 132 using the main etching gas can generate more etching byproducts. During the etching of the film layer 13 to be etched exposed in the second region 132, the top 1321 of the sidewall of the trench 132A can be formed. The deposition of more etching byproducts on the top 1321 of the sidewall of the trench 132A can protect the top 1321 of the sidewall of the trench 132A without the need for additional first sidewall protection gas, preventing the first sidewall protection gas from hindering etching and thus improving etching efficiency.

[0032] Step S120: Referring to Figure 3C, perform the second etching step. Use the main etching gas and the first sidewall protective gas to etch the exposed film layer 13 in the second region 132 to form a trench 132A. The first sidewall protective gas is used to react with the remaining exposed areas of the film layer 13 in the second region 132 during the etching process to generate the first byproduct, so as to prevent the trench 132A from being etched laterally.

[0033] For example, in step S120, since the etchable film layer 13 in the first region 131 has been completely etched, only the etchable film layer 13 in the second region 132 remains exposed. Etching the remaining etchable film layer 13 in the second region 132 using the main etching gas can only generate a small amount of etching byproducts. During the etching of the remaining etchable film layer 13 in the second region 132, the bottom of the sidewall 1322 of the trench 132A can be formed. The small amount of etching byproducts deposited on the bottom of the sidewall 1322 of the trench 132A cannot effectively protect the bottom of the sidewall 1322 of the trench 132A. For example, in related technologies, as shown in FIG1C, the bottom of the sidewall 1322 of the trench 132A is prone to lateral etching. This application, by adding a first sidewall protective gas in step S120, allows the first sidewall protective gas to react with the remaining etchable film layer 13 in the second region 132 to generate a first byproduct. This first byproduct, along with a smaller amount of etching byproduct, is deposited together at the bottom 1322 of the sidewall of the trench 132A, effectively protecting the bottom 1322 of the sidewall and preventing lateral etching. The top 1321 and bottom 1322 of the sidewall of the trench 132A are vertically connected to form the trench 132A.

[0034] In the above scheme, during the first etching step, when the main etching gas simultaneously etches the film layer 13 to be etched in the first region 131 and part of the film layer 13 to be etched in the second region 132, the exposed area of ​​the film layer 13 to be etched is large because both the first region 131 and the second region 132 are exposed. The main etching gas reacts with the film layer 13 to generate more etching byproducts. These byproducts are deposited on the top 1321 of the sidewall of the trench 132A, which can provide sidewall protection without the need to add an additional first sidewall protection gas. This avoids the first sidewall protection gas hindering etching and improves etching efficiency. In the second etching step... In this process, since the etchable film 13 in the first region 131 has been completely etched, only the remaining etchable film 13 in the second region 132 needs to be etched. At this point, only the second region 132 of the etchable film 13 is exposed, reducing the exposed area of ​​the etchable film 13. This reduces the amount of etching byproducts generated by the reaction between the main etching gas and the etchable film 13. The first byproduct generated by the reaction between the first sidewall protection gas and the remaining etchable film 13 in the second region 132 can then co-deposit with the smaller amount of etching byproducts at the bottom 1322 of the sidewall of the trench 132A, providing sidewall protection and preventing lateral etching of the bottom 1322 of the sidewall of the trench 132A. Based on this, this method can effectively improve etching efficiency while ensuring a good sidewall morphology for the trench 132A, thereby improving the fabrication efficiency of the trench 132A.

[0035] In one embodiment, performing the first etching step includes the following steps S111 to S113.

[0036] Step S111: Please refer to Figures 3A to 3B together. When the first etching step is started, monitor the spectral intensity of the characteristic products of the film layer 13 to be etched.

[0037] Step S112: When the spectral intensity of the feature product of the film layer 13 to be etched decreases to a preset multiple of the spectral intensity reference value, the first etching step is stopped; wherein, the spectral intensity reference value is the value when the spectral intensity of the feature product enters a stable state, the preset multiple is a decimal greater than 0 and less than 1, and the preset multiple has an inverse proportional relationship with the aperture ratio of the first opening 15A.

[0038] For example, the material of the film layer 13 to be etched can be an aluminum-copper alloy. Taking the characteristic product of the film layer 13 to be etched as an example, when the first etching step is started, the etching stability of the film layer 13 to be etched in the first region 131 and part of the film layer 13 to be etched in the second region 132 is low. The content of the characteristic product of the film layer 13 to be etched shows a fluctuating increase. At this time, the spectral intensity of the monitored characteristic product also shows a fluctuating increase. For example, as shown in Figure 4, curve 1 represents the actual spectral intensity curve of the characteristic product of aluminum, and curve 2 represents the curve after smoothing the actual spectral intensity curve of the characteristic product of aluminum. During the etching time period of approximately 0s to 15s, the content of aluminum characteristic products was observed to fluctuate and increase. When the first etching step reached the first preset time, the etching of the film layer 13 to be etched gradually stabilized, the content of characteristic products in the film layer 13 to be etched gradually stabilized, and the spectral intensity of the characteristic products also entered a stable state. At this time, the spectral intensity of the characteristic products of the film layer 13 to be etched can be used as the spectral intensity reference value. For example, as shown in Figure 4, the spectral intensity of the aluminum characteristic products at an etching time of approximately 15s, 2200cd, is used as the spectral intensity reference value of the characteristic products of the film layer 13 to be etched. When the etchable film 13 in the first region 131 is completely etched, the content of the characteristic products in the etchable film 13 shows a decreasing trend. When the spectral intensity of the characteristic products in the etchable film 13 decreases to a preset multiple of the spectral intensity reference value, the etching endpoint of the etchable film 13 in the first region 131 can be captured. For example, as shown in Figure 4, when the etching time is monitored to be approximately 47s (i.e., the endpoint 46.7s shown in Figure 4), the spectral intensity B of the aluminum characteristic products decreases to a preset multiple of the spectral intensity reference value, thus capturing the etching endpoint of the etchable film 13 in the first region 131. By controlling the cessation of the first etching step, it can be ensured that the etchable film 13 in the first region 131 is completely etched. The preset multiple can be 0.7, that is, the spectral intensity of the characteristic products in the etchable film 13 decreases to 0.7 times the spectral intensity reference value. It should be noted that the preset multiplier value can be selected and adjusted according to actual needs, and this application embodiment does not impose any restrictions on it.

[0039] For example, the preset factor is inversely proportional to the aperture ratio of the first opening 15A. As shown in Figures 3A and 3B, for example, the larger the aperture ratio of the first opening 15A, the larger the area of ​​the first region 131 exposed by the etched film 13 from the first opening 15A. When the first etching step is performed for the first preset time, the content of the feature products of the etched film 13 is greater. When the etched film 13 in the first region 131 is completely etched, the content of the feature products of the etched film 13 decreases more. Therefore, by setting the preset factor for the decrease in the spectral intensity of the feature products of the etched film 13 to be inversely proportional to the aperture ratio of the first opening 15A, it is beneficial to accurately monitor the change in the etching depth of the etched film 13 in the first region 131.

[0040] In one embodiment, performing the second etching step further includes the following steps S121 to S122.

[0041] Step S121: Please refer to Figures 3B to 3C. During the second etching step, monitor the spectral intensity of the characteristic products of the film layer 13 to be etched.

[0042] For example, continuing with the case where the material of the film layer 13 to be etched is aluminum alloy, the characteristic products of the film layer 13 to be etched are also characteristic products of aluminum. The characteristic products of aluminum are generated during the etching process of the main etching gas etching the remaining film layer 13 to be etched in the second region 132. The change in the content of the characteristic products of aluminum can characterize the change in the etching depth of the remaining film layer 13 to be etched in the second region 132. Since the content of the characteristic products of aluminum is directly proportional to its spectral intensity, the change in the etching depth of the remaining film layer 13 to be etched in the second region 132 can be monitored by monitoring the change in the spectral intensity of the characteristic products of aluminum.

[0043] Step S122: If the spectral intensity of the characteristic product of the film layer 13 to be etched decreases continuously for a preset number of times, stop executing the second etching step; the preset number of times is an integer greater than or equal to 2.

[0044] For example, please refer to Figures 3B, 3C and 5 together. During the etching process of the remaining film layer 13 to be etched in the second region 132, as the etching time t increases, the etching depth of the remaining film layer 13 to be etched in the second region 132 increases accordingly. The content of the characteristic products of the film layer 13 to be etched shows a pattern of first increasing and then decreasing. The spectral intensity of the characteristic products of the film layer 13 to be etched also shows a pattern of first increasing and then decreasing. For example, curve 1 in Figure 5 represents the actual spectral intensity curve of the characteristic products of aluminum, and curve 2 in Figure 5 represents the curve after smoothing the actual spectral intensity curve of the characteristic products of aluminum. In Figure 5, the spectral intensity of the characteristic products of aluminum shows an increasing trend between approximately 15s and 23s during the etching period, and a decreasing trend between approximately 23s and 26s during the etching period. By monitoring the number of consecutive decreases in the spectral intensity of the characteristic products of aluminum, it can be determined that the content of the characteristic products in the film layer 13 to be etched is continuously decreasing. The remaining film layer 13 to be etched in the second region 132 is gradually completely etched, forming the bottom 1322 of the sidewall of the trench 132A, thereby obtaining the trench 132A that penetrates the film layer 13 to be etched.

[0045] Furthermore, during the etching process, if noise appears in the spectral intensity signal, the spectral intensity of the characteristic products of the etched film layer 13 will fluctuate, first rising and then falling within a short period of time. The above scheme avoids the problem of poor monitoring accuracy caused by noise in the spectral intensity signal by setting the number of consecutive decreases in the spectral intensity of the characteristic products of the etched film layer 13 to be greater than or equal to 2, which helps to improve the accuracy of controlling the execution of the second etching step. For example, referring to Figure 5, by sequentially monitoring three spectral intensities A1, A2, and A3 (curve 2) within an etching time period of approximately 24.5s to 25.5s, and A1>A2>A3, for example, A1=1060cd, A2=1050cd, A3=1000cd, it can be determined that the spectral intensity of the aluminum characteristic products decreased twice consecutively.

[0046] In the above scheme, during the second etching step, by monitoring the spectral intensity of the characteristic products of the film layer 13 to be etched, and when the spectral intensity of the characteristic products of the film layer 13 to be etched decreases continuously for a preset number of times, the etching endpoint of the remaining film layer 13 to be etched in the second region 132 can be detected, and the execution of the second etching step can be stopped to ensure that the remaining film layer 13 to be etched in the second region 132 is completely etched and forms the bottom sidewall 1322 of the trench 132A.

[0047] In one embodiment, referring to Figures 3A and 3B together, in the first etching step, the main etching gas reacts with the film layer 13 to be etched in the first region 131 and a portion of the film layer to be etched in the second region 132 to generate a second byproduct. In the second etching step, the main etching gas etches the remaining film layer 13 to be etched in the second region 132 to generate a third byproduct. The amount of the third byproduct generated is less than the amount of the second byproduct generated.

[0048] For example, the main etching gas includes chlorine gas, which can be at least one of boron trichloride (BCl3), chlorine (Cl2), carbon tetrachloride (CCl4), silicon chloride (SiCl4), and hydrogen chloride (HCl). The material of the film layer 13 to be etched can be an aluminum alloy. For example, when the material of the film layer 13 to be etched is an aluminum-copper alloy, the chlorine gas can be boron trichloride and chlorine gas. This is because the volatility of copper byproducts is poor, and boron trichloride has a large bombardment energy, which is beneficial for bombarding and removing copper byproducts. However, the etching rate of aluminum in the film layer 13 is relatively slow due to the low etching rate of boron trichloride. Therefore, using chlorine gas can improve the etching rate of aluminum in the film layer 13. In the first etching step, the second byproduct generated by the main etching gas etching the film layer 13 to be etched in the first region 131 and part of the film layer 13 to be etched in the second region 132 is aluminum chloride (AlCl3). In the second etching step, the third byproduct generated by the main etching gas etching the remaining film layer 13 to be etched in the second region 132 is also aluminum chloride.

[0049] In the above scheme, during the first etching step, the main etching gas reacts with the etchable film 13 in the first region 131 and a portion of the etchable film 13 in the second region 132 to generate a relatively large amount of second byproducts. This is beneficial for the deposition of the second byproducts on the top 1321 of the sidewall of the trench 132A to form a thicker protective film, and the second byproducts provide strong protection for the top 1321 of the sidewall of the trench 132A. During the second etching step, the main etching gas reacts with the remaining etchable film 13 in the second region 132 to generate a relatively small amount of third byproducts, so that the third byproducts can only be deposited in the trench 13. A thin protective film is deposited at the bottom 1322 of the sidewall of trench 2A. The first byproduct compensates for the reduced amount of the third byproduct relative to the second byproduct. This allows the first and third byproducts to deposit together at the bottom 1322 of the sidewall of trench 132A to form a thicker protective film. This results in a stronger protective effect of the first and third byproducts on the bottom 1322 of the sidewall of trench 132A, preventing the main etching gas from laterally etching the bottom 1322 of the sidewall of trench 132A. This helps ensure that the surface of the bottom 1322 of the sidewall of trench 132A is smooth and continuous.

[0050] In one embodiment, during the first and second etching steps, a second sidewall protective gas reacts with the sidewall of trench 132A to generate a fourth byproduct. This fourth byproduct provides weaker protection to the bottom 1322 of the sidewall of trench 132A than to the top 1321. The first byproduct also compensates for the weaker protection provided by the second sidewall protective gas to the bottom 1322 of the sidewall. In some embodiments, the deposition characteristics of the second sidewall protective gas are, for example, less than those of the first sidewall protective gas. Although a second sidewall protective gas is added during the first etching step, its lighter deposition characteristics prevent the generation of excessive fourth byproducts, thus avoiding the second sidewall protective gas from hindering etching and improving etching efficiency.

[0051] For example, during the first etching step, because the etching depth of the film layer 13 to be etched in the second region 132 is relatively shallow, the gas exchange rate at the top of the formed trench 132A is relatively fast. The second sidewall protective gas easily reacts with the top 1321 of the sidewall of the trench 132A and generates a large amount of fourth byproducts. These fourth byproducts deposit on the top 1321 of the sidewall of the trench 132A, providing protection for the top 1321 of the sidewall of the trench 132A. During the second etching step, as the etching depth of the remaining film layer 13 to be etched in the second region 132 increases, the gas exchange rate at the bottom of the formed trench 132A slows down. The reaction between the second sidewall protective gas and the bottom 1322 of the sidewall of the trench 132A generates only a small amount of fourth byproducts. Therefore, the protective ability of the fourth byproducts on the bottom of the sidewall of the trench 132A is weaker than its protective ability on the top 1321 of the sidewall of the trench 132A. In the above scheme, during the second etching step, the first by-product and the fourth by-product are co-deposited on the bottom 1322 of the sidewall of the trench 132A. This allows the first by-product to compensate for the protective ability of the fourth by-product on the bottom 1322 of the sidewall of the trench 132A, thereby effectively protecting the bottom 1322 of the sidewall of the trench 132A and preventing lateral etching from occurring on the bottom 1322 of the sidewall of the trench 132A.

[0052] In one embodiment, the material of the film layer 13 to be etched includes aluminum, the first sidewall protective gas includes a hydrocarbon gas, and the second sidewall protective gas includes a nitrogen-containing gas.

[0053] For example, the material of the film layer 13 to be etched can be an aluminum alloy, the first sidewall protective gas can be a hydrocarbon gas such as trifluoromethane (CHF3), and the second sidewall protective gas can be a nitrogen-containing gas such as nitrogen (N2). During the execution of the first etching step and the second etching step, the nitrogen reacts with the film layer 13 to be etched in the first region 131 and part of the film layer 13 to be etched in the second region 132 to generate a fourth byproduct, which is aluminum nitride (Al). x N y ); where x and y are both positive integers. During the second etching step, trifluoromethane reacts with the remaining etchable film 13 in the second region 132 to generate aluminum monofluoride (AlF) and aluminum nitride (Al x N y The first sidewall protection gas, along with aluminum fluoride (AlF), is deposited together on the bottom 1322 of the sidewall of trench 132A to protect the bottom 1322 of the sidewall. It should be noted that the first sidewall protection gas includes, but is not limited to, trifluoromethane (CHF3). The first sidewall protection gas can be selected and adjusted according to actual needs, as long as it is a hydrocarbon or fluorine-based gas.

[0054] In the related technology, during the process of etching the film layer 13 to be etched using the main etching gas, nitrogen gas is added as a sidewall protection gas. In the process of selecting the first sidewall protection gas and the second sidewall protection gas, the inventors also conducted the following experiments 1 and 2.

[0055] Experiment 1: Based on relevant technologies, the protective capability of nitrogen gas for the bottom sidewall 1322 of trench 132A was improved by increasing the nitrogen flow rate. During Experiment 1, the inventors discovered that although increasing the nitrogen flow rate could improve the protective capability for the bottom sidewall 1322 of trench 132A to some extent, the improvement was limited. The main etching gas would still laterally etch the bottom sidewall 1322 of trench 132A, resulting in the laterally curved morphology of the bottom sidewall 1322 of trench 132A as shown in Figure 1C.

[0056] Experiment 2: Based on the relevant technology, nitrogen was replaced with trifluoromethane, which has redeposition properties, and trifluoromethane was used alone to protect the bottom 1322 of the sidewall of trench 132A. During Experiment 2, the inventors discovered that aluminum monofluoride generated by the reaction of trifluoromethane gas with the remaining etchable film layer 13 in the second region 132 would be over-deposited on the bottom 1322 of the sidewall of trench 132A, causing the bottom 1322 of the sidewall of trench 132A to tilt. For example, the bottom 1322 of the sidewall of trench 132A would form an inverted trapezoidal shape as shown in Figure 1D. Experiments 1 and 2 verified that neither of these methods could make the surface of the bottom 1322 of the sidewall of trench 132A smooth and continuous.

[0057] The above scheme selects a hydrocarbon-fluorine gas as the first sidewall protection gas because hydrocarbon-fluorine gases readily react with aluminum to form easily deposited aluminum monofluoride. Aluminum monofluoride provides stronger protection for the bottom 1322 of the sidewall of trench 132A than aluminum nitride, effectively compensating for the lack of protection provided by aluminum nitride. Therefore, using both nitrogen-containing gas and hydrocarbon-fluorine gas simultaneously in the second etching step ensures a smooth and continuous surface for the bottom 1322 of the sidewall of trench 132A. It should be noted that because hydrocarbon-fluorine gases have heavy deposition characteristics, adding them in the first etching step would cause the top 1321 of the sidewall of trench 132A to become excessively sloping. Therefore, hydrocarbon-fluorine gas is not required as a sidewall protection gas in the first etching step.

[0058] In one embodiment, the flow rates of both the first and second sidewall protective gases range from 2 sccm to 18 sccm (inclusive). For example, the flow rate range of the first sidewall protective gas can be 5 sccm to 15 sccm (inclusive), and the flow rate range of the second sidewall protective gas can be 5 sccm to 10 sccm (inclusive). By selecting flow rates of 2 sccm to 18 sccm for both the first and second sidewall protective gases, it can be ensured that the amount of the first byproduct generated is sufficient to compensate for the protective effect of the fourth byproduct on the bottom sidewall 1322 of the trench 132A, preventing the main etching gas from laterally etching the bottom sidewall 1322 of the trench 132A.

[0059] In one embodiment, referring to Figures 3B and 3C, the material of the mask layer 15 is photoresist. The method further includes: during the execution of the first etching step and the second etching step, the mask layer 15 reacts with the second sidewall protection gas to generate a third sidewall protection gas. The third sidewall protection gas is used to block the main etching gas from lateral etching of the trench 132A.

[0060] For example, the second sidewall protective gas can be nitrogen. During the first and second etching steps, the second sidewall protective gas reacts with the mask layer 15 to generate a carbon- and hydrogen-containing gas (CN gas) with a protective function. The carbon- and hydrogen-containing gas falls into the interior of the trench 132A under the bombardment of the plasma, thereby blocking the main etching gas from laterally etching the sidewall of the trench 132A and playing a sidewall protection role.

[0061] In one embodiment, the aspect ratio of the trench 132A ranges from 3.2 to 4.6 (including the endpoint values).

[0062] In practical applications, the aspect ratio is usually the ratio between the etching depth and the critical dimension (CD) of the metal gate 132B. Since the critical dimension of the metal gate 132B is the same as the opening size of the trench 132A, the aspect ratio of the trench 132A can also be used as an evaluation index for the etching process.

[0063] In related technologies, due to the difference in opening size between the first opening 15A and the second opening 15B, when the etchable film 13 in the first region 131 is completely etched, the etchable film 13 in the second region 132 is only etched to a predetermined depth. That is, only a portion of the etchable film 13 in the second region 132 is etched. Continuing to etch the remaining etchable film 13 in the second region 132 would result in a reduced amount of etching byproducts due to the smaller exposed area of ​​the etchable film 13, thus failing to effectively protect the bottom 1322 of the sidewall of the trench 132A. To ensure a smooth and continuous surface of the bottom 1322 of the sidewall of the trench 132A, the trench formation methods in related technologies can only obtain trenches 132A with an aspect ratio of less than 3.

[0064] Compared to related technologies, this application incorporates a first sidewall protection gas during the second etching step. The first sidewall protection gas reacts with the remaining etchable film layer 13 in the second region 132 to generate a first byproduct. This first byproduct compensates for the reduced amount of the third byproduct compared to the second byproduct, allowing the first and third byproducts to co-deposit at the bottom 1322 of the sidewall of the trench 132A, effectively protecting the bottom 1322 of the sidewall of the trench 132A. Therefore, a trench 132A with an aspect ratio between 3.2 and 4.6 can be obtained, making the method of this application more suitable for forming trenches 132A with a high aspect ratio.

[0065] In one embodiment, as shown in FIG3A, a first barrier layer 12 is provided on the side of the film layer 13 to be etched that faces away from the mask layer 15, and a second barrier layer 14 is provided between the film layer 13 to be etched and the mask layer 15. The method further includes at least one of the following:

[0066] Please refer to Figures 3A to 3B together. Before performing the first etching step, a second barrier layer etching step is performed to expose the first region 131 and the second region 132 of the film layer 13 to be etched.

[0067] Please refer to Figures 3C to 3D together. After performing the second etching step, the first barrier layer etching step is performed so that the trench 132A penetrates the first barrier layer 12.

[0068] For example, the material of the first barrier layer 12 may be titanium nitride (TiN), the material of the second barrier layer 14 may be titanium (Ti) or titanium nitride, and the main etching gas used in the first barrier layer etching step and the second barrier layer etching step may both be chlorine-containing gases, such as boron trichloride and chlorine.

[0069] In the above scheme, before performing the first etching step, a second barrier layer etching step is performed. This completely etches the areas of the second barrier layer 14 exposed from the first opening 15A and the second opening 15B, exposing the first region 131 of the film layer 13 to be etched from the first opening 15A and at least a portion of the second region 132 of the film layer 13 to be etched from the second opening 15B. After performing the second etching step, the first barrier layer etching step is performed, causing the trench 132A to penetrate the first barrier layer 12, ensuring that the trench 132A completely cuts off the film layer 13 to be etched.

[0070] Furthermore, a substrate 11 is disposed on the side of the first barrier layer 12 opposite to the film layer 13 to be etched. The first barrier layer 12 is located between the substrate 11 and the film layer 13 to be etched, which can prevent diffusion and electromigration between the film layer 13 to be etched and the substrate 11. The second barrier layer 14 is located between the film layer 13 to be etched and the mask layer 15, which can also prevent diffusion and electromigration between the film layer 13 to be etched and the mask layer 15.

[0071] In one embodiment, as shown in FIG3A, the etchable film layer 13 may include an isolated area (ISO area) and a dense area. The first area 131 of the etchable film layer 13 is located in the isolated area, and the second area 132 of the etchable film layer 13 is located in the dense area.

[0072] The sparse pattern region is an area with a low density of etched patterns, while the dense pattern region is an area with a high density of etched patterns. The etched pattern in the sparse pattern region is composed of at least one first opening 15A, and the etched pattern in the dense pattern region is composed of multiple second openings 15B. The density of the etched patterns in the sparse and dense pattern regions can be selected and adjusted according to actual needs, and this embodiment does not impose any limitations on this. Furthermore, the ratio of the projected area of ​​the sparse pattern region on the substrate 11 to the projected area of ​​the dense pattern region on the substrate 11 can also be selected and adjusted according to actual needs. For example, configuring...

[0073] The ratio of the orthographic projection area of ​​the sparse pattern region on the substrate 11 to the orthographic projection area of ​​the dense pattern region on the substrate 11 is 1:1.

[0074] The above-described scheme, by placing the first region 131 of the film layer 13 to be etched in a sparse pattern region and the second region 132 of the film layer 13 to be etched in a dense pattern region, allows the etching pattern density of the second region 132 of the film layer 13 to be etched to be denser than that of the first region 131. Consequently, during the first etching step, the main etching gas located in the dense pattern region is consumed more quickly, which also leads to a slower etching rate in the second region 132 of the film layer 13 to be etched than in the first region 131, thus exacerbating the loading effect. In this application scenario with a strong loading effect, the trench formation method of this embodiment can form a smooth and continuous sidewall bottom 1322 of the trench 132A after etching the remaining film layer 13 in the second region 132, thereby ensuring that the trench 132A has a good sidewall morphology.

[0075] The method for forming trenches according to an embodiment of this application will be described in detail below using a specific example. The method for forming trenches according to an embodiment of this application includes sequentially performing a second barrier layer etching step, a first etching step, a second etching step, and a first barrier layer etching step. The process conditions for each process step may include: a process chamber temperature range of -10℃ to 100℃ (inclusive); a process chamber pressure range of 5 mTorr to 100 mTorr (inclusive); an upper electrode power range of 100W to 1000W; a lower electrode power range of 30W to 250W (inclusive); and the main etching gases include chlorine (Cl2) and boron trifluoride (BCl3), with flow rates of both chlorine and boron trifluoride ranging from 2 sccm to 200 sccm (inclusive). The process time for each process step is determined by the thickness of the corresponding film layer and the etching rate. Optionally, the specific process parameters for each step are shown in Table 1 below.

[0076] Table 1. Process parameters for each step in trench formation.

[0077] Please refer to Figures 3A and 3B together. First, perform the second barrier layer etching step. Use chlorine gas (Cl2) and boron trichloride (BCl3) to etch the second barrier layer 14, so that the first region 131 of the film layer 13 to be etched is exposed from the first opening 15A of the mask layer 15, and the second region 132 of the film layer 13 to be etched is exposed from the second opening 15B of the mask layer 15.

[0078] Please refer to Figures 3A and 3B together. Then, perform the first etching step. Chlorine and boron trichloride are used simultaneously to etch the film layer 13 to be etched in the first region 131 and a portion of the film layer 13 to be etched in the second region 132. Nitrogen (N2) is added to the process chamber to remove the film layer 13 to be etched in the first region 131 and to etch a portion of the film layer 13 to be etched in the second region 132, forming the top 1321 of the sidewall of trench 132A. Chlorine is used to etch the film layer 13 to be etched in the first region 131 and a portion of the film layer to be etched in the second region 132, generating a second byproduct, such as aluminum chloride. Nitrogen reacts with the top 1321 of the sidewall of trench 132A to generate a fourth byproduct, such as aluminum nitride. The second and fourth byproducts are deposited together on the top 1321 of the sidewall of trench 132A, protecting the top 1321 of the sidewall of trench 132A. During the first etching step, the etching endpoint of the film 13 to be etched in the first region 131 is determined by monitoring the spectral intensity of the characteristic products of aluminum to drop to 70% of the spectral intensity reference value, and the first etching step is stopped when the etching endpoint is reached. At this time, it can be ensured that the film 13 to be etched in the first region 131 is completely removed, and a portion of the film 13 to be etched in the second region 132 is etched to form the top 1321 of the sidewall of the trench 132A.

[0079] Please refer to Figures 3B to 3C. Next, the second etching step is performed. Chlorine and boron trichloride are used to etch the remaining film layer 13 in the second region 132. Trifluoromethane (CHF3) is introduced into the process chamber to protect the bottom of the sidewall 1322 of the trench 132A with nitrogen and trifluoromethane during the formation of the bottom of the sidewall 1322 of the trench 132A. In this process, chlorine is used to etch the remaining etchable film layer 13 in the second region 132 and generate a third byproduct, such as aluminum chloride, and the amount of the third byproduct generated is less than that of the second byproduct; trifluoromethane is used to react with the remaining etchable film layer 13 in the second region 132 and generate a first byproduct, such as aluminum monofluoride, and the first byproduct is used to compensate for the reduced amount of the third byproduct relative to the second byproduct; nitrogen is used to react with the bottom 1322 of the sidewall of trench 132A to generate a fourth byproduct, and the fourth byproduct has a weaker protective ability on the bottom 1322 of the sidewall of trench 132A than on the top 1321 of the sidewall of trench 132A, and the first byproduct is also used to compensate for the protective ability of the fourth byproduct on the bottom 1322 of the sidewall of trench 132A; the first, third, and fourth byproducts are deposited together on the bottom 1322 of the sidewall of trench 132A to protect the bottom 1322 of the sidewall of trench 132A. During the second etching step, the etching endpoint of the remaining film layer 13 to be etched in the second region 132 is determined by monitoring the spectral intensity of the characteristic products of aluminum to decrease twice consecutively. The second etching step is stopped when this endpoint is reached. At this time, the bottom 1322 of the sidewall of a trench 132A can be formed within the film layer 13 to be etched. The bottom 1322 of the sidewall of the trench 132A and the top 1321 of the sidewall of the trench 132A are vertically connected to form a trench 132A with a smooth sidewall surface and continuous angles. The sidewall angle of the trench 132A can be in the range of 86° to 90° (including the endpoint value). For example, the sidewall angle of the trench 132A can be any value among 86°, 88°, and 90°.

[0080] Please refer to Figures 3C to 3D together. Finally, the first barrier layer etching step is performed. Chlorine gas and boron trichloride are used to etch the area of ​​the first barrier layer 12 exposed from the second opening 15B until the substrate 11 is exposed from the second opening 15B, so that the trench 132A completely cuts off the film layer 13 to be etched.

[0081] This application also provides a method for fabricating a semiconductor device, including the following steps S210 to S220.

[0082] Step S210: Please refer to Figure 3A to form a plurality of semiconductor devices (not shown in the figure). The plurality of semiconductor devices are interconnected by a film layer 13 to be etched. The film layer 13 to be etched includes a first region 131 and a second region 132.

[0083] Step S220: Referring to Figures 3B to 3D, a trench 132A is formed in the second region 132 of the film layer 13 to be etched using the trench forming method of any of the above embodiments, so as to cut off the film layer 13 to be etched and form a plurality of metal gates 132B in the film layer 13 to be etched.

[0084] For example, a plurality of metal gates 132B may correspond one-to-one with a plurality of semiconductor devices to form the gate of each semiconductor device. Alternatively, each metal gate 132B may correspond one-to-one with at least two semiconductor devices to interconnect at least two semiconductor devices.

[0085] It should be noted that in the semiconductor manufacturing field, aspect ratio is commonly used as an evaluation metric for the etching morphology of the metal gate 132B. The aspect ratio of the metal gate 132B is the ratio between the etching depth and the feature size of the metal gate 132B. The feature size is typically equal to the opening size of the second opening 15B. Therefore, the above method can obtain a metal gate 132B with a high aspect ratio. The feature size of the metal gate can be less than 0.15 μm.

[0086] In another related technology, the method for forming a metal gate includes: first etching a dielectric layer to form a trench; then filling the trench with metal to form a metal gate; and finally using a chemical mechanical planarization (CMP) process to remove excess portions of the metal gate. In this related technology, the process for forming the metal gate is complex and costly.

[0087] The above-described solution achieves a breakthrough over conventional techniques by employing an etching process to form a metal gate 132B with a high aspect ratio. Its fabrication process is more streamlined and helps reduce costs. It should be noted that the fabrication method of this semiconductor device adopts all the technical solutions of all the above embodiments, and therefore possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon further here.

[0088] Figure 6 shows a schematic diagram of the structure of a semiconductor process apparatus according to an embodiment of this application.

[0089] As shown in Figure 6, the semiconductor process equipment 200 may include a process chamber 20, an inlet assembly 20A, an upper electrode assembly 20B and a lower electrode assembly 20C, an exhaust assembly 20D, and a controller (not shown in Figure 6). The controller includes at least one processor and at least one memory, in which a computer program is stored. When the computer program is executed by the processor, it implements the method of any of the above embodiments.

[0090] For example, the controller can be a host computer or a slave computer. The controller can open the valve of the air inlet assembly 20A to introduce the corresponding process gas into the process chamber 20; the controller can also control the flow rate of the process gas by controlling the opening degree of the valve of the air inlet assembly 20A. The controller can also control the air extraction assembly 20D to evacuate the interior of the process chamber 20, for example, by controlling the valve opening degree of the air extraction assembly 20D or the speed of the air extraction pump, thereby controlling the pressure inside the process chamber 20 and removing some reaction byproducts.

[0091] The upper electrode assembly 20B may include an RF coil 21, an upper RF power supply 23, and an upper matching unit 25. The controller is also used to control the upper RF power supply 23 to provide RF power to the RF coil 21 through the upper matching unit 25, so that the RF coil 21 excites the process gas inside the process chamber 20 to generate plasma.

[0092] The lower electrode assembly 20C may include a wafer carrier 22, a lower RF power supply 24, and a lower matching unit 26. The controller is also used to control the lower RF power supply 24 to provide RF power to the wafer carrier 22 through the lower matching unit 26 to provide RF bias. The wafer carrier 22 may be, for example, an electrostatic chuck, a mechanical chuck, or a vacuum suction chuck. The wafer carrier 22 is used to carry a wafer 100, on which the film layer 13 to be etched according to embodiments of this application is disposed.

[0093] The semiconductor process equipment 200 in this application embodiment can be an inductively coupled plasma (ICP) device. This application embodiment does not limit the type of semiconductor process equipment 200.

[0094] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0095] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0096] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. All or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware, the program being stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiments.

[0097] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. This storage medium can be a read-only memory, a disk, or an optical disk, etc.

[0098] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of forming a trench, characterized by, The method is applied to a film layer to be etched, wherein a mask layer is disposed on the film layer to be etched, the mask layer having a first opening and a second opening, the opening size of the first opening being larger than the opening size of the second opening, the first opening exposing a first region of the film layer to be etched, and the second opening exposing at least a portion of a second region of the film layer to be etched. The method includes: Perform a first etching step, using a main etching gas to etch the first region and the second region to remove the film layer to be etched in the first region and a portion of the film layer to be etched in the second region; The second etching step is performed, in which the main etching gas and the first sidewall protection gas are used to etch the remaining film layer to be etched in the second region to form a trench. The first sidewall protection gas is used to react with the film layer to be etched exposed in the second region during the etching process to generate a first byproduct, so as to prevent the sidewalls of the trench from being etched laterally.

2. The method of claim 1, wherein, The first etching step includes: When the first etching step is started, the spectral intensity of the characteristic products of the film to be etched is monitored; If the spectral intensity of the feature product of the film to be etched decreases to a preset multiple of the spectral intensity reference value, the first etching step is stopped; wherein, the spectral intensity reference value is the value when the spectral intensity of the feature product enters a stable state, the preset multiple is a decimal greater than 0 and less than 1, and the preset multiple has an inverse proportional relationship with the aperture ratio of the first opening.

3. The method of claim 1, wherein, The second etching step includes: During the second etching step, the spectral intensity of the characteristic products of the film to be etched is monitored; If the spectral intensity of the characteristic product of the film to be etched decreases continuously for a preset number of times, the second etching step is stopped; the preset number of times is an integer greater than or equal to 2.

4. The method according to claim 1, characterized in that, In the first etching step, the main etching gas reacts with the film layer to be etched in the first region and part of the film layer to be etched in the second region to generate a second byproduct; In the second etching step, the main etching gas reacts with the remaining film layer to be etched in the second region to generate a third byproduct; The amount of the third byproduct generated is less than the amount of the second byproduct generated.

5. The method of claim 1, wherein, During the execution of the first etching step and the second etching step, the second sidewall protective gas is also used to react with the sidewall of the trench to generate a fourth byproduct. The fourth byproduct has a weaker protective ability for the bottom of the sidewall of the trench than for the top of the sidewall of the trench. The first byproduct is also used to compensate for the sidewall protection ability of the fourth byproduct for the bottom of the sidewall of the trench.

6. The method of claim 5, wherein, The film to be etched includes aluminum, the first sidewall protective gas includes hydrocarbon and fluorine gases, and the second sidewall protective gas includes nitrogen-containing gases.

7. The method of claim 1, wherein, A first barrier layer is provided on the side of the film layer to be etched away from the mask layer, and a second barrier layer is provided between the film layer to be etched and the mask layer. The method further includes at least one of the following: Before performing the first etching step, a second barrier layer etching step is performed to expose the first region of the film to be etched and the second region of the film to be etched. After performing the second etching step, a first barrier layer etching step is performed to make the trench penetrate the first barrier layer.

8. The method of claim 1, wherein, The film layer to be etched has a sparse pattern region and a dense pattern region. The first region of the film layer to be etched is located in the sparse pattern region, and the second region of the film layer to be etched is located in the dense pattern region.

9. A method of manufacturing a semiconductor device, characterized by, include: Multiple semiconductor devices are formed, and the multiple semiconductor devices are interconnected by a film layer to be etched; the film layer to be etched includes a first region and a second region; The trench is formed in the second region of the film layer to be etched using the trench forming method of any one of claims 1 to 8, so as to cut off the film layer to be etched and form a plurality of metal gates in the film layer to be etched.

10. A semiconductor process apparatus, characterized by, include: The process chamber, the air intake assembly, the upper electrode assembly, the lower electrode assembly, and the controller, the controller including at least one processor and at least one memory, the memory storing a computer program that, when executed by the processor, implements the method as described in any one of claims 1-9.

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