Formation method of semiconductor device

Abstract

A forming method of a semiconductor device comprises the following steps: providing a substrate which is internally provided with STI (Shallow Trench Isolation); etching by-products on the surface of the STI are removed through blowing of first gas, and the first gas is gas without oxygen atoms; and removing oxides on the surface of the STI by adopting a cleaning process. According to the scheme, after shallow trench isolation etching, the phenomenon that the line width size is increased along with the increase of the cleaning waiting time can be effectively inhibited, and the performance and the yield of the device are improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and particularly to a method for forming a semiconductor device. Background Art

[0002] Shallow Trench Isolation (STI, also known as shallow trench isolation) is a common semiconductor manufacturing process that separates components forming a device by digging trenches. In shallow trench isolation etching, how to accurately control the line width dimension of the shallow trench isolation, the depth of the trench, and the top corner radius is very important for the performance and yield of the finally manufactured semiconductor device (hereinafter referred to as the device).

[0003] In the existing semiconductor manufacturing process flow, the STI etching step and the subsequent cleaning step are carried out on different machines. After the wafer completes STI etching on the etching machine, it needs to be transferred to the cleaning machine for cleaning. As the waiting time between etching and cleaning becomes longer, the sidewalls of the silicon trenches are gradually oxidized to form silicon oxide, resulting in an increase in the measured line width dimension (for example, the active region line width dimension), which has a greater impact on the device performance and yield. Summary of the Invention

[0004] The technical problem solved by the present invention is how to suppress the increase in the line width dimension with the increase of the cleaning waiting time after shallow trench isolation etching.

[0005] To solve the above technical problem, an embodiment of the present invention provides a method for forming a semiconductor device, including: providing a substrate having STI therein; using a first gas to blow and remove the etching by-products on the surface of the STI, wherein the first gas is a gas without oxygen atoms; and adopting a cleaning process to remove the oxide on the surface of the STI.

[0006] Optionally, before using the first gas to blow and remove the etching by-products on the surface of the STI, it further includes: using a second gas to perform surface treatment on the surface of the STI, wherein the second gas includes oxygen.

[0007] Optionally, the reaction time of the step of using the second gas to perform surface treatment on the surface of the STI is less than the reaction time of the step of using the first gas to blow and remove the etching by-products on the surface of the STI.

[0008] Optionally, the step of using the first gas to blow and remove the etching by-products on the surface of the STI includes: monitoring the oxygen content in the etching chamber, and using the first gas to blow and remove the etching by-products on the surface of the STI until the oxygen content in the etching chamber drops to a preset threshold.

[0009] Optionally, the step of using the first gas to blow and remove the etching by-products on the STI surface is periodically performed within the waiting time, where the waiting time is the time interval between forming the STI and performing the cleaning process.

[0010] Optionally, the first gas includes an inert gas.

[0011] Optionally, the reaction time of the step of using the cleaning process to remove the oxide on the STI surface is greater than the upper limit of the process specification of the standard reaction time for cleaning the oxide on the STI surface; and / or, the concentration of the cleaning liquid used in the step of using the cleaning process to remove the oxide on the STI surface is greater than the standard concentration of the cleaning liquid used in the cleaning process.

[0012] Optionally, the step of using the cleaning process to remove the oxide on the STI surface includes: obtaining the waiting time since the completion of the step of using the first gas to blow and remove the etching by-products on the STI surface; determining the parameters of the cleaning process according to the waiting time, where the parameters include the concentration of the cleaning liquid and / or the reaction time of the cleaning process; using the cleaning process to remove the oxide on the STI surface according to the determined parameters.

[0013] Optionally, the longer the waiting time, the greater the concentration of the cleaning liquid and / or the longer the reaction time of the cleaning process.

[0014] Optionally, the step of using the cleaning process to remove the oxide on the STI surface includes: using cleaning liquids with multiple cleaning intensities to sequentially clean the surface of the substrate to remove the oxide on the STI surface, where the cleaning intensity of the cleaning liquid gradually decreases as the number of cleaning rounds increases.

[0015] Optionally, the step of using cleaning liquids with multiple cleaning intensities to sequentially clean the surface of the substrate includes: using the same cleaning liquid with a decreasing concentration to sequentially clean the surface of the substrate.

[0016] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0017] The embodiment of the present invention provides a method for forming a semiconductor device, including: providing a substrate with STI therein; using a first gas to blow and remove the etching by-products on the STI surface, where the first gas is a gas without oxygen atoms; using a cleaning process to remove the oxide on the STI surface.

[0018] In the existing shallow trench isolation (STI) etching technology, during the final surface treatment step of etching, introducing oxygen gradually oxidizes the sidewalls of the silicon trenches and generates silicon oxide as the waiting time increases, resulting in an increase in the measured line width dimension. In contrast, in this implementation, by blowing a gas without oxygen atoms on the STI surface to replace the oxygen surface treatment step in the existing etching process, the oxygen residue amount during the waiting time is reduced, thereby decreasing the oxidation rate of the STI surface. As a result, the generation of oxides (such as silicon oxide) can be reduced, and the change in the line width dimension with the waiting time can be slowed down and inhibited.

[0019] Furthermore, first treat the STI surface with an oxygen-containing gas (i.e., the second gas, such as oxygen) to ensure a better etching by-product removal effect. Then, blow a gas without oxygen atoms on the STI surface to reduce or even remove the oxygen atoms remaining on the STI surface, decrease the oxidation rate of the STI surface during the waiting time, and alleviate the influence of the STI surface oxidation on the line width dimension during the waiting time.

[0020] Furthermore, reasonably control the reaction time of treating the STI surface with the oxygen-containing gas, for example, not exceeding the reaction time of blowing with the oxygen-free gas to remove the etching by-products, which is beneficial to reducing the generation of oxides on the STI surface during the reaction time of the oxygen-containing gas.

[0021] Furthermore, by real-time monitoring the oxygen content in the etching chamber during the execution of the surface treatment step, ensure that the oxygen content on the STI surface at the end of the surface treatment step is controlled below a preset threshold to achieve precise removal of the residual oxygen.

[0022] Furthermore, by periodically blowing the STI with the first gas, it is beneficial to avoid the oxidation reaction of the STI that affects the line width dimension after being actively or passively exposed to an oxygen-containing environment during the waiting time.

[0023] Furthermore, by increasing the reaction time of the cleaning process, the cleaning effect can be improved. The enhancement of the cleaning effect is also beneficial to reducing the line width dimension and alleviating the change in the line width dimension with the waiting time.

[0024] Furthermore, by increasing the concentration of the cleaning solution used in the cleaning process, the cleaning ability for oxides can be improved, and the change in the line width dimension with the waiting time can be alleviated.

[0025] Furthermore, by using a cleaning solution with a suitable concentration and / or reaction time according to the length of the waiting time, the parameters of the cleaning process can be flexibly adjusted according to the time interval between the etching step and the cleaning step, while ensuring a better cleaning effect and improving the production efficiency.

[0026] Further, the surface of the substrate is cleaned in sequence with cleaning liquids having decreasing cleaning intensity, which helps to obtain a better cleaning effect while reducing the damage to the oxide-free area on the substrate surface caused by the high-concentration cleaning liquid. Description of the Drawings

[0027] Figure 1 is a flowchart of the existing semiconductor manufacturing process;

[0028] Figure 2 is Figure 1 a graph showing the variation of the line width dimension with the waiting time after the STI etching process in

[0029] Figure 3 is a flowchart of a method for forming a semiconductor device according to an embodiment of the present invention;

[0030] Figure 4 is a schematic diagram of an etching chamber corresponding to the step of removing etching by-products by blowing with a first gas according to an embodiment of the present invention;

[0031] Figure 5 is Figure 1 a flowchart of a specific implementation manner of step S13 in

[0032] Figure 6 is a flowchart of a method for forming a semiconductor device in a typical application scenario according to an embodiment of the present invention.

[0033] Description of the Reference Numerals:

[0034] Etching chamber 100, sensor 110, substrate 120, STI 130, first gas 140, etching by-product 150. Detailed Embodiment

[0035] As described in the background art, in the existing semiconductor manufacturing process flow, after the STI etching step is completed and before the cleaning process, the line width dimension changes with the waiting time during this period, affecting the device performance and yield.

[0036] See Figure 1 , Figure 1 which exemplarily shows part of the process of the existing semiconductor manufacturing process. Specifically, after a substrate (for example, a silicon substrate, on which tetraethyl orthosilicate TEOS, a bottom anti-reflection layer BRAC, and a patterned photoresist layer PR are formed in sequence) undergoes a lithography process, an STI etching process (for example, silicon trench etching) is performed on an etching machine (denoted as model A), and then it is transferred to a cleaning machine (denoted as model B) for a cleaning process. In practice, after the substrate completes the STI etching step on model A, it is very likely that it cannot be immediately transferred to model B for the cleaning process, but needs to wait for a relatively long waiting time.

[0037] The inventors of the present application found through analysis that in the existing STI etching technology, there is a surface treatment step at the end of STI etching. In Model A, oxygen is used to remove by-products (also known as etching by-products) on the surface. Generally speaking, at this time, most of the composition of the substrate is silicon, and the residual oxygen in this surface treatment step will gradually oxidize the sidewalls of the silicon trenches and generate silicon oxide as the waiting time from etching to cleaning (i.e., the aforementioned waiting time, also known as the waiting duration) becomes longer, resulting in an increase in the measured line width dimension CD.

[0038] Figure 2 Yes Figure 1 It is a graph showing the change of the line width dimension CD after the STI etching process in the figure with the waiting time. Figure 2 The abscissa is the waiting time from the end of etching to cleaning (unit: hour), and the ordinate is the measured line width dimension CD (unit: nanometer nm). Combining Figure 2 It can be seen that the longer the waiting time, the more oxides are generated on the STI surface, and the larger the measured line width dimension CD. Especially for the measured line width dimension CD when the waiting time is greater than 18 hours, it is significantly larger than the line width dimensions CD on both sides when the waiting time is less than 2 hours.

[0039] To solve the above technical problems, an embodiment of the present invention provides a method for forming a semiconductor device, including: providing a substrate having STI therein; using a first gas to blow and remove the etching by-products on the surface of the STI, wherein the first gas is a gas without oxygen atoms; adopting a cleaning process to remove the oxides on the surface of the STI.

[0040] Thus, in this implementation, by using a gas without oxygen atoms to blow the surface of the STI, it replaces the oxygen surface treatment step in the existing etching process, reduces the residual amount of oxygen during the waiting time, and thus reduces the oxidation rate of the STI surface. Therefore, the generation of oxides (such as silicon oxide) can be reduced, and the change of the line width dimension with the waiting time can be slowed down and inhibited.

[0041] To make the above objects, features, and beneficial effects of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings.

[0042] Figure 3 It is a flowchart of a method for forming a semiconductor device in an embodiment of the present invention.

[0043] Referring to Figure 3 , the method for forming the semiconductor device may include steps S11 to S13:

[0044] Step S11, providing a substrate having STI therein;

[0045] Step S12, use a first gas to blow and remove the etching by-products on the surface of the STI, where the first gas is a gas without oxygen atoms;

[0046] Step S13, adopt a cleaning process to remove the oxide on the surface of the STI.

[0047] Specifically, the substrate can be, for example, a silicon substrate, or can also be, for example, a semiconductor substrate made of other silicon-containing materials.

[0048] Furthermore, the STI can specifically be a process structure formed on the substrate surface through the STI process. During the STI process, etching by-products may be introduced on the substrate surface, such as on the STI surface. The etching by-products on the STI surface include SiF x and C x H x O and other polymers. In practical applications, the specific components of the etching by-products are related to the etching process used for the STI process on the substrate, and this implementation does not limit this.

[0049] In some embodiments, the first gas can be a single type of gas. Preferably, the first gas can be, for example, an inert gas such as helium or argon.

[0050] In some embodiments, the first gas can also be a mixed gas.

[0051] The mixed gas can be a combination of multiple different types of inert gases. For example, the first gas can be a mixed gas including multiple inert gases such as helium and argon.

[0052] The mixed gas can also be a combination of an inert gas and a non-inert gas without oxygen atoms. Among them, the non-inert gas without oxygen atoms can be, for example, chlorine gas Cl 2 or boron trichloride BCl 3 etc. For example, the first gas can be a mixed gas of argon and chlorine gas.

[0053] Furthermore, when the first gas is a mixed gas including an inert gas and a non-inert gas without oxygen atoms, the proportion of the inert gas in the first gas can be greater than the proportion of the non-inert gas without oxygen atoms. For example, the volume fraction of the inert gas in the first gas can be greater than 60%.

[0054] In a specific implementation, in step S13, when adopting a cleaning process to remove the oxide on the surface of the STI, the residual etching by-products in the STI that are not blown away by the first gas can also be cleaned up at the same time, thereby further reducing the residue of the etching by-products in the STI. Thus, it is beneficial to better reduce the influence of the waiting time on the line width dimension.

[0055] In a typical application scenario, three wafers (e.g., wafer No. 1, wafer No. 4, and wafer No. 5) are taken and subjected to different surface treatment steps to obtain the experimental data of Experiment 1 shown in Table 1. Among them, Table 1 exemplarily shows the change of line width dimensions with waiting time after using the prior art (i.e., using oxygen to remove etching by-products) for wafer No. 1 and wafer No. 4, and, for wafer No. 5, using Figure 3 the solution described in the embodiment shown (i.e., using the first gas to blow and remove etching by-products) to show the change of line width dimensions with waiting time.

[0056] Specifically, for wafer No. 4, after shallow trench etching, the line width dimensions at any two positions (e.g., position 1 and position 2) on wafer No. 4 are randomly measured to obtain the specific values of line width dimension 1 and line width dimension 2. The surface oxygen treatment step is performed on wafer No. 4, and after waiting for more than 18 hours after shallow trench etching, the line width dimensions at the aforementioned position 1 and position 2 on wafer No. 4 are measured for the second time to obtain the specific values of line width dimension 1 and line width dimension 2. Among them, the surface oxygen treatment step is to use oxygen to remove the etching by-products on the STI surface. After the second measurement, a cleaning process is performed on wafer No. 4. After cleaning, the line width dimensions at the aforementioned position 1 and position 2 on wafer No. 4 are measured for the third time to obtain the specific values of line width dimension 1 and line width dimension 2.

[0057] Similarly, for wafer No. 1, the surface oxygen treatment step is adopted, and the line width dimensions at any two positions on wafer No. 1 are measured respectively after STI etching and after cleaning within less than 2 hours of waiting time to obtain the specific values of the corresponding line width dimensions 1 and 2.

[0058] For wafer No. 5, after shallow trench etching, the line width dimensions at any two positions (e.g., position 3 and position 4) on wafer No. 5 are randomly measured to obtain the specific values of line width dimension 1 and line width dimension 2. Instead of performing the surface oxygen treatment step, the first gas is used to blow wafer No. 5, and after waiting for more than 18 hours after shallow trench etching, the line width dimensions at the aforementioned position 3 and position 4 on wafer No. 5 are measured for the second time to obtain the specific values of line width dimension 1 and line width dimension 2. After the second measurement, a cleaning process is performed on wafer No. 5. After cleaning, the line width dimensions at the aforementioned position 3 and position 4 on wafer No. 5 are measured for the third time to obtain the specific values of line width dimension 1 and line width dimension 2.

[0059] The test results of Experiment 1 are shown in Table 1:

[0060] Table 1

[0061]

[0062]

[0063] Experiments show that the line width dimension 1 obtained after cleaning the 4th wafer with a waiting time greater than 18 hours is 98.6 nm. In contrast, the line width dimension 1 obtained after cleaning the 5th wafer with a waiting time greater than 18 hours is 90.3 nm, which is close to the line width dimension 1 (90.5 nm) after the cleaning process under the condition that the waiting time of the 1st wafer is less than 2 hours.

[0064] Similarly, the line width dimension 2 obtained after cleaning the 4th wafer with a waiting time greater than 18 hours is 99.6 nm. In contrast, the line width dimension 2 obtained after cleaning the 5th wafer with a waiting time greater than 18 hours is 95.2 nm, which is close to the line width dimension 2 (93.1 nm) after the cleaning process when the waiting time of the 1st wafer is less than 2 hours.

[0065] It can be seen that by abandoning the existing surface oxygen treatment step and instead using the first gas to blow and remove the etching by-products on the wafer substrate as described in this embodiment, the line width dimension obtained after cleaning after a long waiting time is significantly smaller than the line width dimension measured when the waiting time is the same after the existing surface oxygen treatment step. Therefore, removing the surface oxygen treatment step helps to slow down and inhibit the change of the line width dimension with the waiting time.

[0066] Furthermore, by replacing the surface oxygen treatment step with the step of using the first gas without oxygen to blow and remove the etching by-products, it is possible to control the line width dimension under the condition that the waiting time exceeds 18 hours to be basically the same as the line width dimension when the waiting time is less than 2 hours.

[0067] In a variant, before performing step S12, that is, before using the first gas to blow and remove the etching by-products on the surface of the STI, this embodiment may further include the step of using a second gas to perform surface treatment on the surface of the STI, where the second gas may include oxygen.

[0068] Specifically, in this variant, the surface oxygen treatment step is not completely abandoned to utilize the characteristic that oxygen can react with the etching by-products to obtain a better etching by-product removal effect.

[0069] Further, after utilizing the oxygen reaction and blowing away a part of the etching by-products on the STI surface, a first gas is introduced. On the one hand, the first gas can continue to blow away the remaining etching by-products on the STI surface; on the other hand, the first gas can blow away oxygen and also isolate between the oxygen and the STI surface to prevent oxygen from remaining on the STI surface and reacting with the substrate (e.g., silicon) to form an oxide (e.g., silicon oxide) during the waiting time. Thus, first, an oxygen-containing gas (i.e., the second gas, e.g., oxygen) is used to treat the STI surface to ensure a better etching by-product removal effect. Then, a gas without oxygen atoms is used to blow the STI surface to reduce or even remove the oxygen atoms remaining on the STI surface, reduce the oxidation rate of the STI surface during the waiting time, and alleviate the influence of the STI surface oxidation on the line width dimension during the waiting time.

[0070] In some embodiments, an inert gas with a weight greater than that of the second gas can be selected as the first gas, so that the first gas can naturally settle on the STI surface and play an insulating role between the second gas such as oxygen and the STI surface.

[0071] In some embodiments, the second gas can be a single type of gas, i.e., oxygen. Alternatively, the second gas can also be a mixed gas containing oxygen and other types of gases.

[0072] In some embodiments, the reaction time of the step of using the second gas to perform surface treatment on the STI surface can be less than the reaction time of the step of using the first gas to blow away the etching by-products on the STI surface. Specifically, reasonably controlling the reaction time of the oxygen-containing gas to treat the STI surface, for example, minimizing the reaction time between oxygen and the SIT surface, is beneficial to inhibiting the formation of oxides. Further, reasonably increasing the reaction time between the first gas and the STI surface is beneficial to obtaining a better etching by-product and oxygen removal effect.

[0073] For example, step S12 can be performed in the etching chamber of an etching machine (e.g., the aforementioned model A). The second gas and the first gas can be introduced into the etching machine successively, and the time for introducing the second gas is less than the time for introducing the first gas.

[0074] Figure 4 It is a schematic diagram of the etching chamber 100 corresponding to the step of using the first gas 140 to blow away the etching by-products 150 in an embodiment of the present invention.

[0075] Reference Figure 4 As shown in, the substrate 120 has an STI 130 therein. In some embodiments, the substrate 120 can include a silicon substrate and a TEOS layer formed on the surface of the silicon substrate, and the STI 130 can be formed on the TEOS layer and at least a part of the silicon substrate.

[0076] In step S12, the first gas 140 is used to blow and remove the etching by-products 150 on the surface of the STI 130. For example, after the STI etching is completed on the substrate 120 in the etching chamber 100 to form the STI 130, before the substrate 120 is removed from the etching chamber 100, a second gas (not shown in the figure) can be introduced into the etching chamber 100 first. After waiting for a first duration, the first gas 140 is then introduced into the etching chamber 100, and the first gas 140 is blown towards the surface of the substrate 120 (especially the surface of the STI 130) to remove the etching by-products 150 and the second gas. After introducing the first gas 140, wait for a second duration, and then remove the substrate 120 from the etching chamber 100. Among them, the first duration can be shorter than the second duration.

[0077] In some embodiments, the first gas 140 and the second gas can be introduced into the etching chamber 100 from the same or different gas inlets.

[0078] In a specific implementation, a sensor 110 can be provided in the etching chamber 100 for monitoring the oxygen content in the etching chamber 100. For example, the sensor 110 can be provided on the top wall of the etching chamber 100. In practical applications, the sensor 110 can be provided at any position in the etching chamber 100, such as being provided close to the substrate 120 to obtain a more accurate measurement result of the oxygen content on the surface of the STI.

[0079] Furthermore, step S12 can specifically include the steps of: monitoring the oxygen content in the etching chamber 100 based on the sensor 110, and using the first gas 140 to blow and remove the etching by-products 150 on the surface of the STI 130 until the oxygen content in the etching chamber 140 drops to a preset threshold.

[0080] For example, the total control terminal of the production line (for example, the control terminal for controlling the operation of the etching machine) can obtain the oxygen content monitoring data of the sensor 110 in real time, and stop introducing the first gas 140 into the etching chamber 100 when the monitoring data indicates that the oxygen content in the etching chamber 100 has dropped to the preset threshold.

[0081] Thus, by monitoring the oxygen content in the etching chamber 100 in real time during the surface treatment step, it can be ensured that the oxygen content on the surface of the STI 130 is controlled below the preset threshold at the end of the surface treatment step, and a more accurate removal effect of the residual oxygen can be obtained.

[0082] In some embodiments, the preset threshold can be, for example, 0 or a small numerical range approaching 0.

[0083] In some embodiments, by monitoring the oxygen content in the etching chamber 100 in real time, the execution time of step S12 can be flexibly adjusted. That is to say, the reaction time for surface treatment of the STI 130 using the first gas 140 can be dynamically adjusted according to the oxygen content in the etching chamber 100 monitored by the sensor 110. This is beneficial to improving the production line efficiency.

[0084] In a variant, the sensor 110 is movably disposed within the etching chamber 100. For example, during the etching process, the sensor 110 is moved out of the etching chamber 100, or can be blocked outside by the wall of the etching chamber 100 to avoid affecting the etching effect. For another example, during the execution of step S12, the sensor 110 is moved into the etching chamber 100, or can be exposed within the etching chamber 100 due to the removal of the originally blocking wall, to monitor the change in the oxygen content within the etching chamber 100.

[0085] In a specific implementation, the step of using the first gas 140 to blow and remove the etching by-products on the surface of the STI 130 can be periodically executed during the waiting time.

[0086] In some embodiments, the number of times of periodic execution can be a fixed number such as 1 time, 2 times, etc.

[0087] In some embodiments, the number of times of periodic execution can also be an indefinite number at preset time intervals, where the value of the preset time interval between two adjacent executions can be fixed or not fixed.

[0088] In some embodiments, the number of times of periodic execution can also be determined according to the oxygen content value monitored in real time. For example, it can be set that whenever the oxygen content value on the surface of the STI 130 is detected to be greater than 1%, the first gas 140 is used to blow and perform surface treatment on the STI 130. In this example, the detection result of the oxygen content can be obtained from the sensor 110, for example. Correspondingly, the substrate 120 is stored in the etching chamber 100 during the waiting time. Alternatively, when the substrate 120 is stored in an environment outside the etching chamber 100 during the waiting time, the detection result of the oxygen content can also be obtained from a sensor (not shown in the figure) disposed in the environment where the substrate 120 is located.

[0089] Thus, by periodically using the first gas 140 to blow the STI 130, it is beneficial to avoid the STI 130 from undergoing an oxidation reaction and affecting the line width dimension after being actively or passively exposed to an oxygen-containing environment during the waiting time.

[0090] In a typical application scenario, after the STI etching process is completed on the substrate 120, the substrate 120 can be placed in the etching chamber 100 and wait for cleaning. During the waiting period, the first gas 140 is used to blow and remove the etching by-products on the surface of the STI 130. At the same time, the oxygen content in the etching chamber 100 is monitored by the sensor 110, and the blowing is stopped until the oxygen content in the etching chamber 140 drops to a preset threshold value.

[0091] In some embodiments, after the blowing is stopped, the substrate 120 remains in the etching chamber 100 during the waiting time. During this period, the first gas 140 can be used to blow the surface of the STI 130 periodically (for example, the first gas 140 is blown for 10 minutes every 1 hour). This helps to avoid the unexpected entry of oxygen into the etching chamber 100 during the waiting time and affect the line width dimension.

[0092] In some embodiments, after the blowing is stopped, the substrate 120 can be transferred to a dedicated gas cabinet (such as a nitrogen cabinet, etc.) or a gas purging device (such as a nitrogen purging device) for storage and waiting. When waiting in the gas cabinet or the gas purging device, the first gas 140 can continue to be used to blow the surface of the STI 130.

[0093] In a specific implementation, the concentration of the cleaning solution used in step S13 can be greater than the standard concentration of the cleaning solution used in the cleaning process.

[0094] Specifically, the standard concentration of the cleaning solution used in the cleaning process refers to the concentration of the cleaning solution commonly used in the prior art during the cleaning after STI etching. Taking the cleaning solution as hydrofluoric acid HF as an example, the standard concentration of hydrofluoric acid HF used in the conventional cleaning process is 10A, and the concentration of hydrofluoric acid HF used in step S13 of this embodiment can be increased to 30A (i.e., the volume ratio is 200:1).

[0095] Thereby, the cleaning ability for oxides can be improved, and the change of the line width dimension caused by the waiting time can be alleviated.

[0096] In a typical application scenario, four wafers (e.g., Wafer No. 1, Wafer No. 2, Wafer No. 4, and Wafer No. 6) are cleaned with cleaning liquids of different concentrations to obtain the experimental data of Experiment 2 shown in Table 2. Among them, Table 2 exemplarily shows the changes in the line width dimensions before and after cleaning the Wafer No. 1 and Wafer No. 2 using the prior art (i.e., cleaning with hydrofluoric acid HF with a standard concentration of 10A), and the changes in the line width dimensions before and after cleaning the Wafer No. 4 and Wafer No. 6 using the implementation method described in Step 13 (i.e., cleaning with hydrofluoric acid HF with a concentration greater than the standard concentration of 10A. For example, for Wafer No. 4, hydrofluoric acid HF with a concentration of 30A is used, and for Wafer No. 6, hydrofluoric acid HF with a concentration of 50A is used).

[0097] Specifically, for Wafer No. 2, after shallow trench etching, the line width dimensions at any two positions (e.g., Position 5 and Position 6) on Wafer No. 2 are randomly measured to obtain the specific values of Line Width Dimension 3 and Line Width Dimension 4. After waiting for more than 18 hours since the shallow trench etching, the line width dimensions at the aforementioned Position 5 and Position 6 on Wafer No. 2 are measured for the second time to obtain the specific values of Line Width Dimension 3 and Line Width Dimension 4. After the second measurement, Wafer No. 2 is cleaned with hydrofluoric acid HF with a concentration of 10A. After cleaning, the line width dimensions at the aforementioned Position 5 and Position 6 on Wafer No. 2 are measured for the third time to obtain the specific values of Line Width Dimension 3 and Line Width Dimension 4.

[0098] For Wafer No. 4, after shallow trench etching, the line width dimensions at any two positions (e.g., Position 7 and Position 8) on Wafer No. 4 are randomly measured to obtain the specific values of Line Width Dimension 3 and Line Width Dimension 4. After waiting for more than 18 hours, the line width dimensions at the aforementioned Position 7 and Position 8 on Wafer No. 4 are measured for the second time to obtain the specific values of Line Width Dimension 3 and Line Width Dimension 4. After the second measurement, Wafer No. 4 is cleaned with hydrofluoric acid with a concentration of 30A. After cleaning, the line width dimensions at the aforementioned Position 7 and Position 8 on Wafer No. 4 are measured for the third time to obtain the specific values of Line Width Dimension 3 and Line Width Dimension 4.

[0099] For Wafer No. 6, after shallow trench etching, the line width dimensions at any two positions (e.g., Position 9 and Position 10) on Wafer No. 6 are randomly measured to obtain the specific values of Line Width Dimension 3 and Line Width Dimension 4. After waiting for more than 18 hours, the line width dimensions at the aforementioned Position 9 and Position 10 on Wafer No. 6 are measured for the second time to obtain the specific values of Line Width Dimension 3 and Line Width Dimension 4. After the second measurement, Wafer No. 6 is cleaned with hydrofluoric acid with a concentration of 50A. After cleaning, the line width dimensions at the aforementioned Position 9 and Position 10 on Wafer No. 6 are measured for the third time to obtain the specific values of Line Width Dimension 3 and Line Width Dimension 4.

[0100] Similarly, for Wafer No. 1, the line width dimensions were measured at any two positions on it after STI etching and after cleaning with hydrofluoric acid at a concentration of 10A under the condition that the waiting time was less than 2 hours, and the specific values of the corresponding line width dimensions 1 and 2 were obtained.

[0101] The test results of Experiment 2 are shown in Table 2:

[0102] Table 2

[0103]

[0104] Experiments show that the line width dimension 3 of Wafer No. 1 after cleaning with hydrofluoric acid at a concentration of 10A under the condition that the waiting time is less than 2 hours is 90.5 nm, and the line width dimension 3 of Wafer No. 2 after cleaning with hydrofluoric acid at a concentration of 10A under the condition that the waiting time is greater than 18 hours is 97.7 nm. It can be seen that using a cleaning solution with a standard concentration of 10A cannot alleviate the phenomenon of the change of the line width dimension with the waiting time.

[0105] For Wafer No. 4, the line width dimension 3 after cleaning with hydrofluoric acid at a concentration of 30A under the condition that the waiting time is greater than 18 hours is 90.9 nm. This value is close to the line width dimension 3 (90.5 nm) of Wafer No. 1 and much smaller than the line width dimension 3 (97.7 nm) of Wafer No. 2. It can be seen that the line width dimension after cleaning the oxide on the substrate surface with hydrofluoric acid with a concentration higher than the standard 10A is significantly smaller than the line width dimension after cleaning with hydrofluoric acid at a concentration of 10A under the same waiting time condition. Further, by using a cleaning solution with a higher concentration to clean the substrate, the line width dimension under the condition that the waiting time exceeds 18 hours can be controlled to be basically the same as the line width dimension when the waiting time is less than 2 hours.

[0106] Similarly, the line width dimension 4 of Wafer No. 1 after cleaning with hydrofluoric acid at a concentration of 10A under the condition that the waiting time is less than 2 hours is 93.9 nm, and the line width dimension 4 of Wafer No. 2 after cleaning with hydrofluoric acid at a concentration of 10A under the condition that the waiting time is greater than 18 hours is 100.5 nm. The line width dimension 4 of Wafer No. 6 after cleaning with hydrofluoric acid at a concentration of 50A under the condition that the waiting time is greater than 18 hours is 95.5 nm. This value is smaller than the line width dimension 4 (100.5 nm) of Wafer No. 2 and close to the line width dimension 4 (93.9 nm) of Wafer No. 1.

[0107] Therefore, increasing the concentration of cleaning solutions such as hydrofluoric acid helps to slow down and inhibit the change of the line width dimension with the waiting time.

[0108] In a specific implementation, in step S13, the reaction time of the step of removing the oxide on the surface of the STI by using a cleaning process may be greater than the upper limit value of the process specification of the standard reaction time for cleaning the oxide on the surface of the STI.

[0109] Specifically, the standard reaction time may refer to the usual time used for cleaning a substrate in an existing cleaning process. This usual time may be, for example, a numerical range, and the upper limit value of the process specification of the standard reaction time may be the upper limit value of this numerical range.

[0110] For example, the standard reaction time for cleaning with hydrofluoric acid is 10s - 20s, and 20s is the upper limit value of the process specification. In this example, the reaction time for cleaning with hydrofluoric acid in step S13 may be greater than 20s.

[0111] Furthermore, it is possible to both use a cleaning time greater than the upper limit value of the standard reaction time and use a cleaning solution with a concentration greater than the standard concentration to clean the oxide on the surface of the STI. Thus, a better oxide removal effect can be obtained.

[0112] Thus, the cleaning effect can be improved. The enhancement of the cleaning effect is also beneficial to reducing the line width dimension and alleviating the change in the line width dimension with the waiting time.

[0113] In a specific implementation, referring to Figure 5 , the step of removing the oxide on the surface of the STI by using a cleaning process in step S13 may specifically include steps S31 to S33:

[0114] Step S31, obtaining the waiting time since the completion of the step of blowing and removing the etching by - products on the surface of the STI with the first gas;

[0115] Step S32, determining the parameters of the cleaning process according to the waiting time, where the parameters include the concentration of the cleaning solution and / or the reaction time of the cleaning process;

[0116] Step S33, removing the oxide on the surface of the STI by using a cleaning process according to the determined parameters.

[0117] In some embodiments, in step S31, timing may start from the end of the blowing action of the first gas and end when the substrate is placed in a cleaning machine (for example, model B), and the time during this period is determined as the waiting time.

[0118] In some embodiments, the cleaning machine may include a plurality of cleaning tanks, where the cleaning intensity of the cleaning solution in different cleaning tanks is different.

[0119] Further, in step S33, the cleaning intensity required this time is determined according to the parameters of the cleaning process determined in step S32, and then the substrate is placed in a cleaning tank containing a cleaning solution with the corresponding cleaning intensity.

[0120] Further, the longer the waiting time, the greater the concentration of the cleaning solution and / or the longer the reaction time of the cleaning process. In other words, the longer the waiting time, the greater the cleaning intensity required.

[0121] Thus, according to the length of the waiting time, a cleaning solution with an appropriate concentration and / or a reaction time can be adopted, and various parameters of the cleaning process can be flexibly adjusted according to the time interval between the etching step and the cleaning step, while ensuring a better cleaning effect and improving production efficiency.

[0122] In some embodiments, step S33 may include the steps of: sequentially cleaning the surface of the substrate with cleaning solutions of various cleaning intensities to remove the oxides on the surface of the STI, wherein, as the number of cleaning rounds increases, the cleaning intensity of the cleaning solution gradually decreases.

[0123] For example, the cleaning solutions of various cleaning intensities may be, for example, different types of cleaning solutions, such as hydrofluoric acid, ammonia water, etc.

[0124] Again, the step of sequentially cleaning the surface of the substrate with cleaning solutions of various cleaning intensities includes: sequentially cleaning the surface of the substrate with the same cleaning solution with decreasing concentration. In a possible example, the surface of the substrate may be sequentially cleaned with hydrofluoric acid with concentrations of 50A, 30A, and 10A.

[0125] Thus, it is beneficial to obtain a better cleaning effect while reducing the damage of the high-concentration cleaning solution to the oxide-free area on the surface of the substrate.

[0126] In a typical application scenario, refer to Figure 6 , the formation process of a semiconductor device may include the following steps:

[0127] Step S41, providing a substrate having STI therein;

[0128] Regarding the specific content of step S61, reference may be made to the relevant description above Figures 3 to 4 , which will not be elaborated here.

[0129] Step S42, performing surface treatment on the surface of the STI using a second gas, wherein the second gas includes oxygen;

[0130] Step S43, using a first gas to blow and remove the etching by-products on the surface of the STI;

[0131] Step S44, monitoring the oxygen content in the etching chamber and determining whether it drops to a preset threshold;

[0132] When the judgment result of step S44 is negative, that is, the oxygen content in the etching chamber does not meet the preset threshold, step S43 is performed again;

[0133] Step S45, when the judgment result of step S44 is positive, that is, the oxygen content in the etching chamber meets the preset threshold, step S43 is stopped, and when the substrate is placed in the cleaning machine, the parameters of the cleaning process are determined according to the waiting time, wherein the parameters include the concentration of the cleaning solution and / or the reaction time of the cleaning process;

[0134] Step S46: removing oxide on the surface of the STI by using a cleaning process based on the determined parameters.

[0135] From the above, the solution of this embodiment can provide a method for forming a semiconductor device, by blowing the STI surface with a gas that does not contain oxygen atoms, replacing the oxygen surface treatment step in the existing etching process, reducing the amount of residual oxygen during the waiting time, thereby reducing the oxidation rate of the STI surface. In this way, the generation of oxides (for example, silicon oxide) can be reduced, and the change of line width size caused by the waiting time can be slowed down and suppressed.

[0136] It should be understood that the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article indicates that the associated objects before and after are in an "or" relationship.

[0137] The "plurality" appearing in the embodiments of the present application refers to two or more.

[0138] The first, second, etc. descriptions appearing in the embodiments of the present application are only used for illustration and distinction of the description objects. There is no order, nor do they indicate any special limitation on the number of devices in the embodiments of the present application, and cannot constitute any limitation on the embodiments of the present application.

[0139] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for forming a semiconductor device, characterized in that, comprising: providing a substrate having STI therein; using a first gas to blow and remove etching by-products on the surface of the STI, wherein the first gas is a gas without oxygen atoms; adopting a cleaning process to remove the oxide on the surface of the STI.

2. The method according to claim 1, characterized in that, before using the first gas to blow and remove the etching by-products on the surface of the STI, further comprising: using a second gas to perform surface treatment on the surface of the STI, wherein the second gas includes oxygen.

3. The method according to claim 2, characterized in that, the reaction time of the step of using the second gas to perform surface treatment on the surface of the STI is less than the reaction time of the step of using the first gas to blow and remove the etching by-products on the surface of the STI.

4. The method according to claim 2, characterized in that, the using the first gas to blow and remove the etching by-products on the surface of the STI includes: monitoring the oxygen content in the etching chamber, and using the first gas to blow and remove the etching by-products on the surface of the STI until the oxygen content in the etching chamber drops to a preset threshold.

5. The method according to claim 1, characterized in that, the step of using the first gas to blow and remove the etching by-products on the surface of the STI is periodically performed within a waiting time, wherein the waiting time is the time interval between forming the STI and performing the cleaning process.

6. The method according to claim 1, characterized in that, the first gas includes an inert gas.

7. The method according to claim 1, characterized in that, the reaction time of the step of adopting a cleaning process to remove the oxide on the surface of the STI is greater than the upper limit value of the process specification of the standard reaction time for cleaning the oxide on the surface of the STI; and / or, the concentration of the cleaning liquid used in the step of adopting a cleaning process to remove the oxide on the surface of the STI is greater than the standard concentration of the cleaning liquid used in the cleaning process.

8. The method according to claim 1, characterized in that, the adopting a cleaning process to remove the oxide on the surface of the STI includes: obtaining the waiting time since the completion of the step of using the first gas to blow and remove the etching by-products on the surface of the STI; determining the parameters of the cleaning process according to the waiting time, wherein the parameters include the concentration of the cleaning liquid and / or the reaction time of the cleaning process; adopting a cleaning process to remove the oxide on the surface of the STI according to the determined parameters.

9. The method according to claim 8, characterized in that, the longer the waiting time, the greater the concentration of the cleaning liquid and / or the longer the reaction time of the cleaning process.

10. The method according to claim 1, characterized in that, the adopting a cleaning process to remove the oxide on the surface of the STI includes: successively cleaning the surface of the substrate with cleaning liquids of multiple cleaning intensities to remove the oxide on the surface of the STI, wherein as the number of cleaning rounds increases, the cleaning intensity of the cleaning liquid gradually decreases.

11. The method according to claim 10, characterized in that, The step of cleaning the surface of the substrate with cleaning liquids having various cleaning intensities in sequence includes: Cleaning the surface of the substrate with the same cleaning liquid in sequence with the concentration decreasing from high to low.

Images