Semiconductor structure surface pretreatment method
By forming film layers with different thermal conductivity on the upper surface of the semiconductor structure, and measuring the average temperature difference using the temperature measurement unit to quickly judge the degree of pretreatment, the problem of difficulty in quickly determining the degree of pretreatment of the metal layer surface oxide layer in the prior art is solved, and the protection of film layer quality and product yield is achieved.
Patent Information
- Application Number
- CN202510300502.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-13
- Publication Date
- 2025-06-13
AI Technical Summary
In the prior art semiconductor device production process, it is difficult to quickly judge the degree of pretreatment of the surface oxide layer on the metal layer, and the monitoring process affects the quality of the film layer.
By forming a first film layer with a thermal conductivity different from the second film layer on the upper surface of the semiconductor structure, and measuring the average temperature difference before and after the pretreatment is used to measure the degree of removal of the second film layer, and determining whether to perform pretreatment again based on the threshold value.
It realizes rapid and simple judgment of the degree of pretreatment, avoids the impact on the quality of the film layer, improves the yield of the product, and unifies the judgment criteria for the degree of removal of the second film layer during the pretreatment process.
Smart Images
Figure CN120149264A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of semiconductor integrated circuit manufacturing and relates to a method for surface pretreatment of semiconductor structures. Background Art
[0002] In semiconductor processes, copper has excellent electrical conductivity and low resistance and is commonly used as the interconnect metal in the back end. However, copper is extremely easy to oxidize, and a layer of copper oxide will form on the exposed surface of copper interconnect lines, thereby increasing the resistance and affecting the performance and stability of semiconductor devices. Therefore, it is very important to treat the copper oxide on the copper surface. In the back-end process, NDC (nitrogen-doped silicon carbide) is deposited on the copper surface as a dielectric barrier layer. Before the deposition of NDC, the copper surface needs to be pretreated and the removal degree of the oxide layer needs to be monitored. At present, the reaction degree of copper oxide is often monitored by the hydrogen ion concentration, and then the removal degree of the oxide layer is reflected. However, this method will cause hill-like protrusions on the surface of the copper layer, affecting the electrical conductivity of the copper layer; the removal degree of the oxide layer can also be determined by the change in reflectivity, but the equipment for measuring reflectivity is usually set outside the pretreatment equipment, and the time from measuring the reflectivity to entering the next process station will also generate copper oxide that slightly affects the electrical conductivity of the copper layer; XPS can also be used for elemental analysis, but this method takes a long time.
[0003] Therefore, there is an urgent need to find a method for surface pretreatment of semiconductor structures that can simply and quickly judge the pretreatment degree and does not affect the film quality. Summary of the Invention
[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for surface pretreatment of semiconductor structures, which is used to solve the problems in the prior art that it is difficult to quickly judge the pretreatment degree of the oxide layer on the surface of the metal layer in the back-end process of semiconductor device manufacturing and the monitoring process affects the quality of the film layer.
[0005] To achieve the above object and other related objects, the present invention provides a method for surface pretreatment of semiconductor structures, including the following steps:
[0006] Provide a semiconductor structure with a first film layer and a second film layer stacked in sequence on an upper surface layer, and the thermal conductivity of the first film layer is different from that of the second film layer;
[0007] Heat the semiconductor structure at a first preset temperature for a first preset time, and measure the first average temperature of the upper surface of the semiconductor structure by using a temperature measuring unit at the same time when the heating ends;
[0008] After preprocessing the second film layer, heat the semiconductor structure at the first preset temperature for the first preset time again, and measure the second average temperature on the upper surface of the semiconductor structure by using the temperature measurement unit at the same time when the heating ends;
[0009] Judge the difference between the first temperature difference between the first average temperature and the second average temperature and the first threshold. If the first temperature difference is less than the first threshold, repeat the steps of preprocessing, heating, measuring the second average temperature of the semiconductor structure, and judging the difference between the new first temperature difference and the first threshold. If the second temperature difference is not less than the first threshold, perform subsequent processes.
[0010] Optionally, the semiconductor structure further includes a substrate wafer and a dielectric layer stacked in sequence, and the first film layer is located on the upper surface of the dielectric layer.
[0011] Optionally, the material of the first film layer includes copper, aluminum, titanium, and tungsten.
[0012] Optionally, the thickness of the second film layer is less than the thickness of the first film layer.
[0013] Optionally, the second film layer includes an oxide layer of the first film layer.
[0014] Optionally, the difference between the thermal conductivity of the first film layer and the thermal conductivity of the second film layer is not less than 50 Wm -1 K -1 。
[0015] Optionally, the range of the first preset temperature is 25°C to 50°C; the first preset time is not greater than 15 s.
[0016] Optionally, the temperature measurement unit can also measure the temperature distribution on the upper surface of the semiconductor structure and output a temperature distribution map of the upper surface of the semiconductor structure. After preprocessing the semiconductor structure, when measuring the second average temperature on the upper surface of the semiconductor structure, it further includes the steps of measuring the temperature distribution on the upper surface of the semiconductor structure and presenting the temperature distribution map of the upper surface of the semiconductor structure.
[0017] Optionally, if the first temperature difference is greater than the first threshold, it further includes the step of determining the relative position of the residual area of the second film layer based on the temperature distribution map of the upper surface of the preprocessed semiconductor structure.
[0018] The present invention also provides another method for preprocessing the surface of a semiconductor structure, including the following steps:
[0019] Provide a semiconductor structure with a first film layer and a second film layer stacked in sequence formed on an upper surface layer, and the thermal conductivity of the first film layer is different from the thermal conductivity of the second film layer;
[0020] Pre-treat the semiconductor structure and heat the semiconductor structure at a second preset temperature for a second preset time. At the end of the heating, use a temperature measurement unit to measure the temperatures of a plurality of measurement regions evenly distributed on the upper surface of the semiconductor structure.
[0021] Judge the difference between a second temperature difference between the measurement region with the highest temperature and the measurement region with the lowest temperature and a second threshold. If the second temperature difference is greater than the second threshold, repeat the steps of pre-treating, heating, measuring the temperatures of the respective measurement regions, and judging the difference between the new second temperature difference and the second threshold. If the second temperature difference is not greater than the second threshold, perform subsequent processes.
[0022] As described above, the surface pre-treatment method of the semiconductor structure of the present invention improves the pre-treatment degree monitoring method. The semiconductor structure is heated at a preset temperature for a preset time. Since there is a large difference in the thermal conductivity coefficients of the first film layer and the second film layer on the upper surface layer of the semiconductor structure, there will be an obvious difference in the average temperature before and after the surface pre-treatment of the semiconductor structure, and there will also be an obvious difference between the residual region of the second film layer and the non-residual region. According to the temperature difference between the average temperatures before and after the pre-treatment or the difference between the temperature difference between the measurement region with the highest temperature and the measurement region with the lowest temperature after the pre-treatment and the corresponding threshold, determine the removal degree of the second film layer after the pre-treatment, and based on the removal degree of the second film layer, decide whether to perform the pre-treatment process, measure the temperature difference, and judge the relationship between the temperature difference and the threshold again. The monitoring method is simple and fast, the monitoring process has no influence on the film layer quality, the yield of the product is improved, and at the same time, through the setting of the threshold, the judgment standard for the removal degree of the second film layer in the pre-treatment process is unified, which is convenient for quickly judging the pre-treatment degree, and then convenient for monitoring the pre-treatment process of batch products; by measuring the temperature distribution map on the upper surface of the semiconductor structure after the pre-treatment with a temperature measurement unit, the residual position of the second film layer after the pre-treatment can be quickly determined, which is convenient for the analysis of the pre-treatment degree and the improvement of the pre-treatment process, and has high industrial utilization value. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It shows a process flow chart of a surface pre-treatment method of a semiconductor structure of the present invention.
[0024] Figure 2 It shows a schematic cross-sectional structure diagram of a semiconductor structure before pre-treatment of a surface pre-treatment method of a semiconductor structure of the present invention.
[0025] Figure 3 It shows a schematic cross-sectional structure diagram of a semiconductor structure after pre-treatment of a surface pre-treatment method of a semiconductor structure of the present invention.
[0026] Figure 4Shown is another process flow diagram of the surface pretreatment method of the semiconductor structure of the present invention.
[0027] Figure 5 Shown is another schematic cross-sectional structure diagram of the semiconductor structure after pretreatment of the surface pretreatment method of the semiconductor structure of the present invention.
[0028] Figure 6 Shown as Figure 5 the top view of the semiconductor structure in
[0029] Explanation of the reference numerals in the attached drawings
[0030] 1 Semiconductor structure
[0031] 11 Substrate wafer
[0032] 12 Dielectric layer
[0033] 13 First film layer
[0034] 14 Second film layer
[0035] 15 Measurement area Detailed implementation manners
[0036] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0037] Please refer to Figures 1 to 6 . It should be noted that the drawings provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.
[0038] Example 1
[0039] This embodiment provides a surface pretreatment method for a semiconductor structure. As Figure 1 shown, it is the process flow diagram of the surface pretreatment method for the semiconductor structure, including the following steps:
[0040] S1-1: Provide a semiconductor structure with a first film layer and a second film layer stacked in sequence on the upper surface, and the thermal conductivity of the first film layer is different from that of the second film layer;
[0041] S1-2: Heat the semiconductor structure at a first preset temperature for a first preset time, and measure the first average temperature of the upper surface of the semiconductor structure by using a temperature measuring unit simultaneously when the heating ends;
[0042] S1-3: After preprocessing the second film layer, heat the semiconductor structure at the first preset temperature for the first preset time again, and measure the second average temperature of the upper surface of the semiconductor structure by using the temperature measuring unit simultaneously when the heating ends;
[0043] S1-4: Judge the difference between the first temperature difference between the first average temperature and the second average temperature and a first threshold value. If the first temperature difference is less than the first threshold value, repeat the steps of preprocessing, heating, measuring the second average temperature of the semiconductor structure, and judging the difference between the new first temperature difference and the first threshold value. If the second temperature difference is not less than the first threshold value, perform subsequent processes.
[0044] Please refer to Figures 2 to 3 , and execute steps S1-1, S1-2 and S1-3: Provide a semiconductor structure 1 with a first film layer 13 and a second film layer 14 stacked in sequence on an upper surface layer. The thermal conductivity of the first film layer 13 is different from that of the second film layer 14; Heat the semiconductor structure 1 at a first preset temperature for a first preset time, and measure the first average temperature of the upper surface of the semiconductor structure 1 by using a temperature measuring unit simultaneously when the heating ends; After preprocessing the second film layer 14, heat the semiconductor structure 1 at the first preset temperature for the first preset time again, and measure the second average temperature of the upper surface of the semiconductor structure 1 by using the temperature measuring unit simultaneously when the heating ends.
[0045] As an example, as Figure 2 shown, it is a schematic cross-sectional structure diagram of the semiconductor structure 1 before preprocessing. The semiconductor structure 1 further includes a substrate wafer 11 and a dielectric layer 12 stacked in sequence. The first film layer 13 is located on the upper surface of the dielectric layer 12.
[0046] Specifically, the substrate wafer 11 is usually a wafer for the back-end process including multiple semiconductor devices to be fabricated, and at the same time, the substrate wafer 11 is also a process platform for forming the dielectric layer 12.
[0047] It should be noted that the size, shape and structure of the substrate wafer 11 are related to the incoming materials of the previous process, which are not limited here.
[0048] Specifically, the dielectric layer 12 is usually used to isolate the substrate wafer 11 from the first film layer 13 and at the same time for insulation between the substrate wafer 11 and the first film layer 13.
[0049] Specifically, the thickness of the dielectric layer 12 can be selected according to the actual situation while ensuring the performance of the subsequent fabricated device.
[0050] Specifically, the material of the dielectric layer 12 includes silicon oxide, silicon nitride, silicon oxynitride, TEOS layer or other suitable dielectric materials. Preferably, the TEOS layer is used as the dielectric layer 12.
[0051] As an example, the material of the first film layer 13 includes copper, aluminum, titanium, tungsten or other suitable materials. Since copper has excellent electrical conductivity and low resistance, preferably, the copper layer is used as the first film layer 13.
[0052] It should be noted that the first film layer 13 in this embodiment is usually used to fabricate the interconnect layer for the corresponding electrode interconnection in the substrate wafer 11. In the fabrication of the interconnect structure of semiconductor devices, an NDC (nitrogen-doped silicon carbide) layer covering the upper surface of the first film layer 13 is usually deposited as a dielectric barrier layer to prevent the metal in the first film layer 13 from diffusing into the dielectric layer. To ensure the performance of the semiconductor device, the second film layer 14 on the upper surface of the first film layer 13 needs to be completely removed.
[0053] Specifically, the thickness of the first film layer 13 can be selected according to the actual situation while ensuring the performance of the subsequent fabricated semiconductor device.
[0054] As an example, the second film layer 14 includes the oxide layer of the first film layer 13 or other suitable materials. In this embodiment, the oxide layer of the first film layer 13 is the second film layer 14, and the second film layer 14 needs to be removed as clean as possible before depositing the NDC layer.
[0055] Specifically, when the second film layer 14 is the oxide layer of the first film layer 13, it can be oxidized by introducing a preset flow rate of oxygen into the process chamber of a CVD (chemical vapor deposition) device or a PVD (physical vapor deposition) device, or by high-temperature oxidation in a furnace tube, or by natural oxidation in a dust-free natural environment (these processes may cause the first film layer 13 to be exposed to an easily oxidizable environment due to the need for other process steps, resulting in the appearance of the second film layer 14 on the first film layer 13).
[0056] As an example, the thickness of the second film layer 14 is less than that of the first film layer 13.
[0057] Specifically, the thickness of the second film layer 14 is usually less than that of the first film layer 13, so the second film layer 14 can heat up faster, a temperature difference can be generated between the first film layer 13 and the second film layer 14, and the amount of the second film layer 14 covering the first film layer 13 can affect the average temperature of the surface.
[0058] Specifically, the thickness of the second film layer 14 is not greater than 500 nm. For example, the thickness of the second film layer 14 is 200 nm, 300 nm, or 400 nm.
[0059] Specifically, by making the thickness of the second film layer 14 relatively thin, it is possible to reduce the excessive thinning of the thickness of the first film layer 13 caused by forming the second film layer 14 using an oxidation process, and avoid affecting the performance of subsequent device fabrication.
[0060] As an example, the difference between the thermal conductivity of the first film layer 13 and the thermal conductivity coefficient of the second film layer 14 is not less than 50 Wm -1 K -1 , so that under the condition of heating at the same temperature for the same time, the temperature on the surface of the semiconductor structure 1 where the second film layer 14 is removed is significantly different from the temperature on the surface of the semiconductor structure 1 where the second film layer 14 remains on the upper surface of the first film layer 13, facilitating the measurement by the temperature measurement unit.
[0061] Specifically, by forming the second film layer 14 with a large difference in thermal conductivity coefficient on the surface of the first film layer 13, the exposed upper surface of the first film layer 13 is covered by the second film layer 14, facilitating the measurement of the first average temperature on the surface of the subsequent semiconductor structure 1.
[0062] It should be noted that the material of the first film layer 13 in this embodiment is a copper layer, and its thermal conductivity is about 400 Wm - 1 K -1 , the material of the second film layer 14 is a copper oxide layer, and its thermal conductivity is about 24 Wm -1 K -1 , based on the thermal conductivities of the first film layer 13 and the second film layer 14 on the upper surface layer of the semiconductor structure 1, the thickness of the second film layer 14 is limited to not greater than 500 nm to ensure that there is a significant difference between the upper surface of the first film layer 13 and the upper surface of the second film layer 14 after heating at the same temperature for the same time. After thinning a part of the thickness of the second film layer 14 and then heating at the same temperature and for the same heating time, there is no obvious difference from the surface of the semiconductor structure 1 after the first heating. Therefore, when heating at the same temperature for the same time, when it can be ensured that there is a temperature difference that can be resolved by the temperature measurement unit on the surface of the semiconductor structure 1 before and after pretreatment, the thickness of the second film layer 14 can also be other suitable thickness values.
[0063] As an example, the range of the first preset temperature is 25°C to 50°C. For example, the first preset temperature can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C. Preferably, the first preset temperature is 45°C to avoid the influence of the ambient temperature.
[0064] Specifically, by setting the heating temperature between 25°C and 50°C, the heating-up time of the semiconductor structure 1 can be reduced, facilitating the shortening of the measurement time before and after pretreatment. Meanwhile, when the first film layer 13 is made of metal, it can also prevent the first film layer 13 from reacting with oxygen at a high temperature after the subsequent removal of the second film layer 14, which may affect the performance of the semiconductor device to be fabricated later, thus ensuring the quality of the first film layer 13 after pretreatment during the monitoring process.
[0065] It should be noted that, under the condition of ensuring the performance of the semiconductor device to be fabricated later, the first preset temperature can also be other suitable temperature values, and the first preset temperature is generally not lower than the ambient temperature before heating to avoid the ambient temperature affecting the measurement result of the temperature measurement unit.
[0066] As an example, the first preset time is not greater than 15 s. For example, the first preset time can be 5 s, 8 s, 10 s, or 12 s.
[0067] Specifically, by setting the heating time of the semiconductor structure 1 to be not greater than 15 s, it can prevent the heating time of the semiconductor structure 1 from being too long, which may cause the temperature on the upper surface of the semiconductor structure 1 to be almost equal to the heating temperature, resulting in no difference in the temperature on the upper surface of the semiconductor structure 1 before and after measurement after heating.
[0068] It should be noted that if there is a significant difference in the temperature between the upper surface of the semiconductor structure 1 with the second film layer 14 not completely removed and the upper surface of the semiconductor structure 1 with the second film layer 14 completely removed after the same heating time at the same temperature before and after pretreatment, the first preset time can also be other suitable values.
[0069] Specifically, the temperature measurement unit includes an infrared thermal imager or other devices with the characteristic of non-contact temperature measurement, and its size, dimensions, and shape can be selected according to the actual situation.
[0070] Specifically, as Figure 3 shown, it is a schematic cross-sectional structure diagram of the semiconductor structure 1 after pretreatment. Usually, a wet etching process is used to pretreat the semiconductor structure 1, and a pretreatment reagent is used to remove the second film layer 14 on the upper surface of the first film layer 13. Under the condition of ensuring the quality of the first film layer 13 after pretreatment, the dosage and components of the pretreatment reagent can be selected according to the actual situation.
[0071] Specifically, during the process of using the pretreatment reagent to treat the second film layer 14 on the upper surface of the first film layer 13, it is usually affected by various environmental factors, resulting in the complete removal of the second film layer 14 in some areas and the remaining second film layer 14 in some areas within the same time, which may affect the performance of the semiconductor device to be fabricated later.
[0072] Specifically, steps S1-4 are performed: judging the difference between the first temperature difference between the first average temperature and the second average temperature and the first threshold value. If the first temperature difference is less than the first threshold value, steps of preprocessing the semiconductor structure 1 again, heating, measuring the second average temperature, and judging the difference between the new second temperature difference and the first threshold value are performed. If the second temperature difference is not less than the first threshold value, subsequent processes are carried out.
[0073] Specifically, since the first film layer 13 is relatively thin, before preprocessing, the upper surface of the first film layer 13 is covered with a second film layer 14 with a relatively low thermal conductivity. After heating, the temperature of the upper surface of the semiconductor structure 1 is relatively low. After preprocessing, when heating again, the temperature of the area where the second film layer 14 is not left on the upper surface of the first film layer 13 will increase significantly compared with that before preprocessing, while the temperature of the area where the second film layer 14 remains changes little.
[0074] Specifically, the first threshold value is used to quantitatively evaluate the remaining situation of the second film layer 14 after preprocessing. Its specific value needs to be set according to the thickness of the second film layer 14, the thermal conductivity, the thermal conductivity of the first film layer 13, and process requirements. For example, if the first film layer 13 is a copper layer and the second film layer 14 is a 300-nm-thick copper oxide layer, when the first temperature difference is greater than 0.2 °C, the remaining copper oxide has little influence on the performance of the fabricated semiconductor device, so the first threshold value can be set to 0.2 °C.
[0075] Specifically, by setting the first threshold value, when the first temperature difference before and after preprocessing is not less than the first threshold value, the remaining of the second film layer 14 has no influence on the subsequent processes. Monitoring the degree of preprocessing can also make the degree of preprocessing have a unified standard, which is convenient for monitoring the preprocessing process of batch products and improving the yield of subsequent products.
[0076] As an example, the temperature measurement unit can also measure the temperature distribution on the upper surface of the semiconductor structure 1 and output a temperature distribution map of the upper surface of the semiconductor structure 1. After preprocessing the semiconductor structure 1, while measuring the second average temperature on the upper surface of the semiconductor structure 1, it also includes the step of measuring the temperature distribution on the upper surface of the semiconductor structure 1 and outputting a temperature distribution map of the upper surface of the semiconductor structure 1, that is, while the temperature measurement unit measures the average temperature on the upper surface of the semiconductor structure 1, it can also measure the temperature distribution on the upper surface of the semiconductor structure 1 and perform temperature distribution imaging.
[0077] Specifically, in the temperature distribution map output by the temperature measurement unit, different temperature regions show different colors, which is convenient for analyzing the surface defects of the semiconductor structure 1 through the color distribution in the temperature distribution map.
[0078] As an example, when the first temperature difference is greater than the first threshold value, it also includes the step of determining the relative position of the remaining area of the second film layer 14 based on the temperature distribution map of the upper surface of the preprocessed semiconductor structure 1.
[0079] Specifically, since the thermal conductivity of the second film layer 14 is less than that of the first film layer 13 (less in this embodiment, which may be greater in other scenarios), when the upper surface of the pre-treated first film layer 13 has the second film layer 14 remaining, the temperature measured by the temperature measurement unit in the area of the remaining second film layer 14 will be lower than that in the non-remaining area. Subsequently, in the temperature distribution map of the upper surface of the pre-treated semiconductor structure 1, an area with a different color from other areas will appear. Subsequently, the remaining area of the second film layer 14 can be determined, facilitating targeted pre-treatment for the remaining area during subsequent re-pre-treatment. At the same time, the pre-treatment process can be improved based on the distribution of the area with the remaining second film layer 14, for example, increasing the removal strength of the pre-treatment for the second film layer 14.
[0080] It should be noted that generally, the thermal conductivities of film layers with different materials and different qualities are different. By measuring the side surface of the heated semiconductor structure 1 with the temperature measurement unit and based on the temperature distribution map of the side surface of the semiconductor structure 1 measured by the temperature measurement unit, the approximate distribution of different film layers along the stacking direction of the first film layer 13 and the second film layer 14 can also be distinguished.
[0081] Specifically, based on the difference in thermal conductivity between the first film layer 13 and the second film layer 14, the temperature measurement unit measures the average temperature of the upper surface of the semiconductor structure 1 heated at a first preset temperature for a first preset time before and after pre-treatment, and calculates the first temperature difference between the first average temperature of the upper surface of the semiconductor structure 1 before pre-treatment and the second average temperature of the upper surface of the semiconductor structure 1 after pre-treatment. Then, the first temperature difference is compared with a first threshold value to quickly determine whether the removal degree of the second film layer 14 after pre-treatment meets the standard for the next process, unifying the evaluation standard for the pre-treatment degree, facilitating the quick judgment of the pre-treatment degree, and then facilitating the monitoring of the pre-treatment process for batch products. The monitoring method is simple and fast, the monitoring process has no impact on the film layer quality, and at the same time, through the monitoring of this pre-treatment process, the treatment effect of the pre-treatment process can be ensured, and the yield of the product can be improved.
[0082] Specifically, by measuring the temperature distribution map of the upper surface of the pre-treated semiconductor structure 1 with the temperature measurement unit, based on this temperature distribution map, the remaining situation of the second film layer 14 after pre-treatment and the relative position of the remaining second film layer 14 can be quickly judged, facilitating the analysis of the pre-treatment degree. At the same time, the pre-treatment process can be improved based on the distribution of the remaining second film layer 14 after pre-treatment.
[0083] The surface pretreatment method of the semiconductor structure 1 in this embodiment improves the monitoring method based on the difference in the thermal conductivity coefficients of the first film layer 13 and the second film layer 14 on the upper layer of the semiconductor structure 1. Before pretreatment, steps of increasing the temperature to a first preset temperature for a first preset time and using a temperature measurement unit to measure the first average temperature of the upper surface of the semiconductor structure 1 after the temperature increase are added. After pretreatment, steps of increasing the temperature to the first preset temperature for the first preset time and using the temperature measurement unit to measure the second average temperature of the upper surface of the semiconductor structure 1 after the temperature increase again are added. Based on the first temperature difference between the first average temperature and the second average temperature, it is possible to quickly determine whether the residue of the second film layer 14 after pretreatment meets the standard. At the same time, by setting a first threshold, the judgment standard for the removal degree of the second film layer 14 is unified, facilitating the quick judgment of the pretreatment degree, and then facilitating the monitoring of the pretreatment process of batch products. The monitoring method is simple and fast, the monitoring process has no impact on the film layer quality, and the yield of the product is improved; by measuring the temperature distribution map of the upper surface of the semiconductor structure 1 after pretreatment with the temperature measurement unit, the residue position of the second film layer 14 after pretreatment can be quickly determined, facilitating the analysis of the pretreatment degree and the improvement of the pretreatment process.
[0084] Embodiment 2
[0085] This embodiment also provides another surface pretreatment method for a semiconductor structure, as Figure 4 shown, which is a process flow chart of another surface pretreatment method for the semiconductor structure, including the following steps:
[0086] S2-1: Provide a semiconductor structure with a first film layer and a second film layer stacked in sequence on the upper layer, where the thermal conductivity coefficient of the first film layer is greater than that of the second film layer (in this embodiment, greater is used, and in other scenarios, it can also be less, as long as they are different);
[0087] S2-2: Pretreat the semiconductor structure and heat the semiconductor structure to a second preset temperature for a second preset time. At the same time when the heating ends, use a temperature measurement unit to measure the temperatures of a plurality of measurement areas evenly distributed on the upper surface of the semiconductor structure;
[0088] S2-3: Judge the difference between the second temperature difference between the measurement area with the highest temperature and the measurement area with the lowest temperature and a second threshold. If the second temperature difference is greater than the second threshold, repeat the steps of pretreating the semiconductor structure, heating, measuring the temperatures of each measurement area, and judging the difference between the new second temperature difference and the second threshold. If the second temperature difference is not greater than the second threshold, proceed to the subsequent process.
[0089] Please refer to Figures 5 to 6, perform steps S2-1 and S2-2: Provide a semiconductor structure 1 with a first film layer 13 and a second film layer 14 stacked in sequence on an upper surface layer, where the thermal conductivity of the first film layer 13 is greater than that of the second film layer 14; preprocess the semiconductor structure 1 and heat the semiconductor structure 1 at a second preset temperature for a second preset time, and at the end of the heating, use a temperature measurement unit to measure the temperatures of a plurality of measurement regions 15 evenly distributed on the upper surface of the semiconductor structure 1.
[0090] It should be noted that the semiconductor structure 1 in this embodiment is the same as the semiconductor structure 1 in Embodiment 1, and the specific structure of the semiconductor structure 1 will not be described in detail here. The formation methods of the first film layer 13 and the second film layer 14 are also the same as those of the first film layer 13 and the second film layer 14 in Embodiment 1, and will not be elaborated here.
[0091] Specifically, the difference in thermal conductivity between the first film layer 13 and the second film layer 14 is not less than 50 Wm -1 K -1 , so that when heated for the same time, there is a significant temperature difference between the region where the second film layer 14 remains on the surface of the semiconductor structure 1 and the region where the second film layer 14 does not remain (the magnitude of the difference in thermal conductivity may have a larger selection range based on the performance improvement of subsequent detection devices. In this embodiment, the difference in thermal conductivity is not less than 50 Wm -1 K -1) ).
[0092] Specifically, the thickness of the first film layer 13 can be selected according to the actual situation while ensuring the performance of the subsequent fabricated semiconductor device.
[0093] Specifically, the second film layer 14 is an oxide film layer of the first film layer 13. In order to reduce the loss amount of the first film layer 13 and ensure the performance of the subsequent fabricated device, usually the thickness of the second film layer 14 is at the nanometer level. Preferably, the thickness of the second film layer 14 is not greater than 500 nm.
[0094] Specifically, as Figure 5 and Figure 6 shown, they are respectively another cross-sectional structure schematic diagram of the preprocessed semiconductor structure 1 and Figure 5 the top view of the semiconductor structure 1 in
[0095] Specifically, during the process of treating the second film layer 14 on the upper surface of the first film layer 13 with a pretreatment reagent, various environmental factors may have an impact, resulting in the complete removal of the second film layer 14 in some areas and the residue of the second film layer 14 in some areas within the same time, which affects the performance of the subsequent fabricated semiconductor device.
[0096] It should be noted that when removing the second film layer 14 on the upper surface of the first film layer 13, it is necessary to ensure that the second film layer 14 in at least some areas is completely removed to facilitate the subsequent analysis of the residue of the second film layer 14 (if less of the second film layer 14 is removed during the treatment process, the steps of treatment and measurement can be cycled).
[0097] Specifically, the range of the second preset temperature is 25°C to 50°C. For example, the second preset temperature can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C. Preferably, the second preset temperature is 45°C to avoid the influence of the ambient temperature.
[0098] Specifically, by making the heating temperature between 25°C and 50°C, the heating-up time of the semiconductor structure 1 can be reduced, facilitating the shortening of the measurement time. At the same time, when the first film layer 13 is a metal, it can also prevent the first film layer 13 from reacting with oxygen at a higher temperature, which affects the performance of the subsequent fabricated semiconductor device.
[0099] It should be noted that under the condition of ensuring the performance of the subsequent fabricated semiconductor device, the second preset temperature can also be other suitable temperature values, and the second preset temperature is usually not lower than the ambient temperature before heating to avoid the influence of the ambient temperature on the measurement result of the temperature measurement unit.
[0100] Specifically, the second preset time is not greater than 15 s. For example, the second preset time can be 5 s, 8 s, 10 s, 12 s.
[0101] Specifically, by making the heating time of the semiconductor structure 1 not greater than 15 s, it is possible to avoid the overlong heating time of the semiconductor structure 1, making the temperature on the upper surface of the semiconductor structure 1 almost equal to the heating temperature, resulting in no difference in the temperature on the upper surface of the semiconductor structure 1 after heating.
[0102] Specifically, the temperature measurement unit includes an infrared thermal imager or other devices with a thermal imaging temperature sensor, and its size, dimensions, and shape can be selected according to the actual situation.
[0103] Specifically, under the condition of ensuring the accuracy of subsequent measurements, the distribution mode and the number of measurement regions 15 on the upper surface of the semiconductor structure 1 can be selected according to the actual situation; the distance between two adjacent measurement regions 15 can be selected according to the actual situation; the sizes and shapes of the respective measurement regions 15 can be selected according to the actual situation.
[0104] It should be noted that the measurement regions 15 can be adjacent regions, that is, the upper surface of the entire semiconductor structure 1 is divided into multiple regions, and each region serves as a measurement region 15 to ensure the accuracy of measurement result analysis.
[0105] Specifically, please execute step S2-3: Determine the difference between the second temperature difference between the measurement region 15 with the highest temperature and the measurement region 15 with the lowest temperature and the second threshold. If the second temperature difference is greater than the second threshold, perform the steps of preprocessing, heating, measuring the temperatures of the respective measurement regions 15, and determining the difference between the new second temperature difference and the second threshold on the semiconductor structure 1 again. If the second temperature difference is not greater than the second threshold, proceed to the subsequent process.
[0106] Specifically, after preprocessing, the entire wafer is heated at the second preset temperature for an appropriate time. Since the thermal conductivity of the first film layer 13 is greater than that of the second film layer 14, when there is a residue of the second film layer 14 on the upper surface of the first film layer 13 and the heating time is the same, the temperature of the region with the residual second film layer 14 will be significantly lower than the temperature of the region where the upper surface of the first film layer 13 is exposed. Subsequently, by determining the temperature difference between the region with the residual second film layer 14 in the semiconductor structure 1 and the region where the upper surface of the first film layer 13 is exposed in the semiconductor structure 1, the influence degree of the residual second film layer 14 on the upper surface of the first film layer 13 after preprocessing on the device performance can be judged.
[0107] Specifically, the second threshold is used to quantitatively judge the influence degree of the thickness of the second film layer 14 in the region where the second film layer 14 remains on the upper surface of the first film layer 13 on the device performance. Generally, the second threshold is determined by the difference in thermal conductivity between the first film layer 13 and the second film layer 14 and the influence of the residual amount of the second film layer 14 on the device performance. The greater the difference in thermal conductivity between the first film layer 13 and the second film layer 14, the greater the value of the second threshold; the thicker the thickness of the second film layer 14 in the region where the second film layer 14 remains on the upper surface of the first film layer 13 and it has no influence on the device performance, the greater the value of the second threshold. Therefore, its specific value needs to be selected according to the actual situation and is not limited here.
[0108] Specifically, if in each measurement area 15, the temperature difference between the measurement area 15 with the highest temperature and the measurement area 15 with the lowest temperature is less than or equal to the second threshold value, it indicates that the amount of the second film layer 14 remaining on the upper surface of the first film layer 13 is small and does not affect the performance of the device, then the subsequent process can be carried out; if in each measurement area 15, the temperature difference between the measurement area 15 with the highest temperature and the measurement area 15 with the lowest temperature is greater than the second threshold value, it indicates that the thickness of the second film layer 14 remaining on the upper surface of the first film layer 13 after pretreatment is large and will affect the performance of the device. In order to ensure the performance and yield of the device to be fabricated subsequently, it is necessary to repeat the steps of pretreatment, measuring the temperature of each measurement area 15, and judging the difference between the temperature of the measurement area 15 with the highest temperature and the temperature of the measurement area 15 with the lowest temperature and the second threshold value until, in each measurement area 15, the temperature difference between the measurement area 15 with the highest temperature and the measurement area 15 with the lowest temperature is less than the second threshold value, and then carry out the subsequent process.
[0109] Specifically, the temperature measurement unit can also measure the temperature distribution on the upper surface of the semiconductor structure 1 and output a temperature distribution map of the upper surface of the semiconductor structure 1. When measuring the temperature of each measurement area 15 on the upper surface of the semiconductor structure 1, it also includes the step of measuring the temperature distribution on the upper surface of the semiconductor structure 1 and outputting a temperature distribution map of the upper surface of the semiconductor structure 1.
[0110] Specifically, based on the temperature distribution map collected by the temperature measurement unit, the position of the remaining area of the second film layer 14 can be judged by the distribution of the color areas corresponding to different temperatures in the map, which is convenient for targeted treatment.
[0111] It should be noted that due to the differences in the thermal conductivity coefficients of different materials or different film layer qualities, the temperature on the longitudinal section of the semiconductor structure 1 shows stratification. Then, the temperature measurement unit can collect the temperature on the longitudinal section of the semiconductor structure 1 and analyze the stacking situation of the film layers in the semiconductor structure 1.
[0112] Specifically, since only one temperature measurement is carried out in this method, the temperature measurement unit can be set in the process chamber of the subsequent process after pretreatment to monitor the pretreatment degree. After pretreatment, it is directly monitored in the process chamber of the subsequent process, without the need to set up a new monitoring process point, saving the process volume and monitoring time in the production line.
[0113] Specifically, after pre-treatment, the semiconductor structure 1 is heated by utilizing the difference in thermal conductivity between the first film layer 13 and the second film layer 14. Then, the temperature of each measurement area 15 is measured by a temperature measurement unit, and the second threshold is used as the standard for quantitative judgment. If the difference between the temperature of the highest temperature measurement area 15 and the temperature of the lowest temperature measurement area 15 is greater than the second threshold, the steps of re-performing pre-treatment, measuring the temperature of each measurement area 15, and judging the difference between the temperature of the new highest temperature measurement area 15 and the temperature of the lowest temperature measurement area 15 and the second threshold are carried out. This unifies the judgment standard for the treatment degree of the second film layer 14 during the pre-treatment process. The monitoring process has no impact on the film layer quality, facilitating the rapid judgment of the pre-treatment degree, and then facilitating the monitoring of the pre-treatment process for batch products. The monitoring method is simple and fast, improving the yield of the products.
[0114] Specifically, while measuring the temperature of each measurement area 15, the temperature distribution map of the upper surface of the semiconductor structure 1 is measured. Based on this temperature distribution map, the residual situation of the second film layer 14 after pre-treatment and the area where the second film layer 14 remains can be quickly judged, facilitating the analysis of the pre-treatment degree and the improvement of the subsequent pre-treatment process.
[0115] The pre-treatment method of the semiconductor structure 1 in this embodiment improves the pre-treatment degree detection method. After pre-treatment, the temperature of each measurement area 15 on the upper surface of the semiconductor structure 1 is detected by a temperature measurement unit. Based on the difference between the second temperature difference between the highest temperature measurement area 15 and the lowest temperature measurement area 15 and the second threshold, it can be quickly judged whether the residue of the second film layer 14 after pre-treatment meets the standard. At the same time, by setting the second threshold, the judgment standard for the treatment degree of the second film layer 14 during the pre-treatment process is unified, facilitating the rapid judgment of the pre-treatment degree, and then facilitating the monitoring of the pre-treatment process for batch products. The monitoring method is simple and fast, the monitoring process has no impact on the film layer quality, and the yield of the products is improved; by measuring the temperature distribution map of the upper surface of the pre-treated semiconductor structure 1 by a temperature measurement unit, the residual position of the second film layer 14 after pre-treatment can be quickly determined, facilitating the analysis of the pre-treatment degree and the improvement of the pre-treatment process.
[0116] In summary, the surface pretreatment method of the semiconductor structure of the present invention improves the pretreatment degree monitoring method. By utilizing the characteristic that the thermal conductivity coefficients of the first film layer and the second film layer have a large difference, after heating the semiconductor structure at a preset temperature for a preset time, there will be a significant difference in the average temperature of the upper surface of the semiconductor structure before and after pretreatment, and there will also be an obvious difference between the residual area of the second film layer and the non-residual area. According to the temperature difference before and after pretreatment or the difference between the temperature difference between the highest temperature measurement area and the lowest temperature measurement area after pretreatment and the corresponding threshold, it is determined whether to perform the pretreatment process again, measure the temperature difference and judge the relationship between the temperature difference and the threshold. The monitoring method is simple and fast, the monitoring process has no impact on the film layer quality, the yield of the product is improved, and at the same time, through the setting of the threshold, the judgment standard for the removal degree of the second film layer in the pretreatment process is unified, which is convenient for quickly judging the pretreatment degree, and then convenient for monitoring the pretreatment process of batch products; by measuring the temperature distribution map of the upper surface of the semiconductor structure after pretreatment through the temperature measurement unit, the residual position of the second film layer after pretreatment can be quickly determined, which is convenient for analyzing the pretreatment degree and improving the pretreatment process. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.
[0117] The above embodiments are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.
Claims
1. A method for pretreating a semiconductor structure surface, characterized in that: The following steps are involved: Provide a semiconductor structure having a first film layer and a second film layer stacked in sequence formed on an upper surface, wherein the thermal conductivity of the first film layer is different from the thermal conductivity of the second film layer; Heating the semiconductor structure at a first preset temperature for a first preset time, and measuring a first average temperature of the upper surface of the semiconductor structure using a temperature measurement unit when the heating is completed; After pre-treating the second film layer, heating the semiconductor structure again at the first preset temperature for a first preset time, and measuring a second average temperature of the upper surface of the semiconductor structure by using the temperature measurement unit when the heating is finished; The difference between a first temperature difference between the first average temperature and the second average temperature and a first threshold value is determined. If the first temperature difference is less than the first threshold value, the semiconductor structure is pretreated, heated, the second average temperature is measured, and the difference between the new first temperature difference and the first threshold value is determined. If the second temperature difference is not less than the first threshold value, subsequent processes are performed.
2. The semiconductor structure surface pretreatment method according to claim 1, characterized in that: The semiconductor structure also includes a substrate wafer and a dielectric layer stacked in sequence, and the first film layer is located on the upper surface of the dielectric layer.
3. The semiconductor structure surface pretreatment method according to claim 1, characterized in that: The material of the first film layer includes copper, aluminum, titanium, and tungsten.
4. The semiconductor structure surface pretreatment method according to claim 1, characterized in that: The thickness of the second film layer is smaller than the thickness of the first film layer.
5. The semiconductor structure surface pretreatment method according to claim 1, characterized in that: The second film layer includes an oxide layer of the first film layer.
6. The semiconductor structure surface pretreatment method according to claim 1, characterized in that: The difference between the thermal conductivity of the first film layer and the thermal conductivity of the second film layer is not less than 50Wm -1 K -1 .
7. The semiconductor structure surface pretreatment method according to claim 1, characterized in that: The first preset temperature ranges from 25° C. to 50° C.; the first preset time is no more than 15 seconds.
8. The semiconductor structure surface pretreatment method according to claim 1, characterized in that: The temperature measurement unit can also measure the temperature distribution on the upper surface of the semiconductor structure and output a temperature distribution map on the upper surface of the semiconductor structure. After preprocessing the semiconductor structure, while measuring the second average temperature on the upper surface of the semiconductor structure, it also includes the steps of measuring the temperature distribution on the upper surface of the semiconductor structure and outputting the temperature distribution map on the upper surface of the semiconductor structure.
9. The semiconductor structure surface pretreatment method according to claim 8, characterized in that: The first temperature difference is greater than the first threshold, and further includes a step of determining a relative position of the second film layer residual area based on a temperature distribution diagram of the upper surface of the semiconductor structure after preprocessing.
10. A method for pretreating the surface of a semiconductor structure, characterized in that: The following steps are involved: Provide a semiconductor structure having a first film layer and a second film layer stacked in sequence formed on an upper surface, wherein the thermal conductivity of the first film layer is different from the thermal conductivity of the second film layer; Pre-treating the semiconductor structure and heating the semiconductor structure at a second preset temperature for a second preset time, and measuring the temperatures of a plurality of measurement areas uniformly distributed on the upper surface of the semiconductor structure using a temperature measurement unit when the heating is finished; Determine the difference between the second temperature difference between the measurement area with the highest temperature and the measurement area with the lowest temperature and a second threshold value, if the second temperature difference is greater than the second threshold value, pre-treat the semiconductor structure again, heat it, measure the temperature of each of the measurement areas and determine the difference between the new second temperature difference and the second threshold value, if the second temperature difference is not greater than the second threshold value, proceed to subsequent processes.