A thin film deposition method
By implementing a temperature control strategy of constant cooling rate and constant temperature increase rate during thin film deposition, the problem of film growth uniformity affected by temperature distribution unevenness is solved, and the film's on-chip uniformity and the overall performance of semiconductor devices are significantly improved.
Patent Information
- Application Number
- CN202411969723.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-04-04
AI Technical Summary
In the prior art, the uniformity of thin film growth is affected by the temperature distribution unevenness and the difference in wafer thermal conduction rate caused by the furnace body heating structure, resulting in increased performance consistency and quality control difficulty of semiconductor devices.
By implementing a constant cooling rate and a constant temperature increase rate during the thin film deposition stage, the reaction chamber temperature is dynamically adjusted so that the temperature at different locations on the wafer is more uniform, the temperature distribution of the entire wafer is optimized, and the actual temperature difference inside and outside the wafer is equalized by precisely controlling the temperature change rate.
It significantly improves the in-chip uniformity of the film, optimizes the growth conditions of the film, and improves the overall performance and reliability of semiconductor devices.
Smart Images
Figure CN119753633A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a thin film deposition method. Background Art
[0002] In the field of semiconductor manufacturing, thin film growth is a crucial process step that directly determines the performance and quality of semiconductor devices. The uniformity of thin film growth, especially the intra-wafer uniformity within the wafer, is one of the key factors affecting the consistency of device performance. However, in the actual production process, the uniformity of thin film growth is restricted by many factors.
[0003] First of all, the furnace heating structure is one of the important factors affecting the uniformity of thin film growth. At present, many thin film growth equipment uses a cylindrical open furnace formed by a resistance wire for heating. Although this heating structure is simple and effective, it will inevitably lead to slight differences in the temperature distribution inside the furnace. In particular, the center of the furnace is often at a lower temperature due to the relatively long heat transfer path and the influence of heat loss. This uneven temperature distribution will directly affect the film growth rate at different locations on the wafer.
[0004] Secondly, the difference in the thermal conductivity rate of the wafer is also an important reason for the uneven growth of the thin film. As the substrate for thin film growth, the thermal conductivity rate of the wafer is affected by many factors such as material, size, and surface state. Due to the different relative positions of the center and edge of the wafer and the heating structure of the furnace, as well as the difference in the thermal conductivity rate of the wafer itself, there is a difference in temperature between the center and edge of the wafer. This temperature difference will cause different film growth rates at different positions on the wafer, thus affecting the uniformity of the film within the wafer.
[0005] In summary, the temperature distribution difference inside the furnace caused by the furnace heating structure and the temperature difference at different positions on the wafer caused by the difference in the thermal conductivity rate of the wafer act together on the thin film growth process, affecting the uniformity of thin film growth inside the wafer. This not only reduces the performance consistency of semiconductor devices, but also increases the difficulty of quality control in the production process. Therefore, how to improve the uniformity of thin film growth has become a technical problem that needs to be solved urgently in the current semiconductor manufacturing field. Summary of the invention
[0006] In view of the problem of poor uniformity of thin films at different positions on a wafer in the prior art, the present application provides a thin film deposition method. The thin film deposition method implements the steps of cooling a reaction chamber from a first temperature to a second temperature at a constant cooling rate and heating the reaction chamber from the second temperature to a third temperature at a constant heating rate during the thin film deposition stage, thereby effectively reducing the temperature difference caused by the heating structure in different areas of the furnace body; by dynamically adjusting the temperature, the temperature at different positions on the wafer is made more uniform, thereby optimizing the temperature distribution of the entire wafer; by utilizing the slow heat conduction characteristic of the wafer, by accurately controlling the temperature change rate, the actual temperature difference between the inside and outside of the wafer is effectively balanced, thereby significantly improving the in-wafer uniformity of the thin film.
[0007] An embodiment of the present application provides a thin film deposition method, comprising the following steps:
[0008] S1, placing the wafer to be coated on a wafer boat and sending it into a reaction chamber, wherein the reaction chamber has an initial temperature;
[0009] S2, raising the temperature of the reaction chamber to a first temperature;
[0010] S3, lowering the temperature of the reaction chamber from the first temperature to a second temperature at a constant cooling rate, and introducing a reaction gas during the cooling process, so that the reaction gas deposits a thin film on the wafer;
[0011] S4, raising the temperature of the reaction chamber from the second temperature to a third temperature at a constant heating rate, and introducing a reaction gas during the heating process, so that the reaction gas continues to deposit a thin film on the wafer;
[0012] S5, lowering the temperature of the reaction chamber from the third temperature to the initial temperature;
[0013] Wherein, the constant cooling rate is greater than the constant heating rate.
[0014] As an implementation manner, the constant cooling rate in step S3 is between 0.5°C / min and 2°C / min.
[0015] As an embodiment, the difference between the first temperature and the second temperature is no greater than 35°C.
[0016] As an implementation manner, the constant heating rate in step S4 is between 0.5°C / min and 2°C / min.
[0017] As an implementation manner, the total thickness of the thin film deposited on the wafer in step S3 and step S4 is between 500 angstroms and 700 angstroms.
[0018] As an implementation manner, the material of the thin film deposited on the wafer in step S3 and step S4 is silicon nitride or silicon oxide.
[0019] As an embodiment, the first temperature is between 700°C and 1000°C.
[0020] As an implementation manner, the third temperature is 1% to 1.5% lower than the first temperature.
[0021] As an implementation manner, after step S4 and before step S5, steps S2 to S4 are further repeated for a preset number of times.
[0022] As an embodiment, the initial temperature is between 400°C and 800°C; and the heating rate when the temperature of the reaction chamber is raised from the initial temperature to the first temperature is between 5°C / min and 10°C / min.
[0023] As described above, the thin film deposition method of the present application has the following beneficial effects:
[0024] The thin film deposition method of the present application implements a specific temperature control strategy during the thin film deposition stage, that is, the temperature of the reaction chamber is reduced from a first temperature to a second temperature at a constant cooling rate, and then the temperature is increased from the second temperature to a third temperature at a constant heating rate. This can significantly reduce the temperature difference caused by the heating structure in different areas of the furnace body, and dynamically adjust the temperature to make the temperature distribution in different areas of the furnace more uniform, thereby providing favorable conditions for the uniform growth of the thin film. By implementing a constant cooling rate and a constant heating rate, combined with the slow heat conduction characteristics of the wafer, the actual temperature difference inside and outside the wafer is effectively balanced, so that the temperatures at different positions on the wafer are closer, and the uniformity of the thin film within the wafer is significantly improved. By accurately controlling the temperature change during the deposition process, not only the temperature difference is reduced, but also the growth conditions of the thin film are optimized, which helps to obtain a thin film with a denser structure and better performance, and is beneficial to improving the overall performance of semiconductor devices. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 Shown is a schematic flow chart of a thin film deposition method according to Embodiment 1 of the present invention.
[0026] Figure 2 The figure shows the comparison of the inhomogeneity of the wafer at different positions after a silicon nitride film (500 angstroms) is deposited on the wafer using the existing thin film deposition method and the thin film deposition method according to the first embodiment of the present invention.
[0027] Figure 3 A schematic diagram showing the flow of a thin film deposition method according to a second embodiment of the present invention. DETAILED DESCRIPTION
[0028] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.
[0029] The processing equipment used for growing thin films on wafers in the prior art includes vertical furnaces and horizontal furnaces. Since vertical furnaces are widely used in the semiconductor and electronics manufacturing industries, the vertical furnace is taken as an example for explanation below.
[0030] Due to the limitations of the furnace structure and the layout of the resistance wire, the temperature at the center of the vertical furnace is often low, while the temperature at the edge is relatively high. This uneven temperature distribution poses a challenge to the growth of thin films. At the same time, in the process methods in the prior art, only the temperature setting value of each area and the film deposition time are adjusted to adjust the uniformity between wafers and the stability of the deposited film thickness. However, due to the low thermal conductivity of the wafer, there is a temperature difference between the center point and the edge of the wafer. This temperature difference will also affect the growth rate of the film. Therefore, the process methods in the prior art do not have a significant effect on the adjustment of the uniformity within the wafer.
[0031] In view of the above defects, the present application provides a thin film deposition method, which is now described in detail through the following embodiments.
[0032] Embodiment 1
[0033] This embodiment provides a thin film deposition method, such as Figure 1 As shown, the thin film deposition method comprises the following steps:
[0034] S1, placing the wafer to be coated on a wafer boat and sending it into a reaction chamber, where the reaction chamber has an initial temperature;
[0035] S2, raising the temperature of the reaction chamber from the initial temperature to a first temperature;
[0036] S3, lowering the temperature of the reaction chamber from the first temperature to the second temperature at a constant cooling rate, and introducing a reaction gas during the cooling process, so that the reaction gas deposits a thin film on the wafer;
[0037] S4, raising the temperature of the reaction chamber from the second temperature to the third temperature at a constant heating rate, and introducing a reaction gas during the heating process, so that the reaction gas continues to deposit a thin film on the wafer;
[0038] S5, lowering the temperature of the reaction chamber from the third temperature to the initial temperature;
[0039] Among them, the constant cooling rate is greater than the constant heating rate.
[0040] After the temperature of the reaction chamber is raised from the initial temperature to the first temperature in step S2, there is no need to undergo a heat preservation process, because the heat preservation process is not conducive to improving the uniformity of the wafer film within the wafer, and will also increase the time of the entire process.
[0041] The process time taken for the reaction chamber to decrease from the first temperature to the second temperature in step S3 may be the same as the process time taken for the reaction chamber to increase from the second temperature to the third temperature in step S4. Since the constant cooling rate in step S3 is greater than the constant heating rate in step S4, the first temperature is greater than the third temperature.
[0042] When the temperature of the reaction chamber in step S3 is reduced from the first temperature to the second temperature, the temperature of the wafer gradually decreases from the center position to the edge position; when the temperature of the reaction chamber in step S4 is increased from the second temperature to the third temperature, the temperature of the wafer gradually increases from the edge position to the center position. The thickness of the thin film deposited by the reaction gas on the wafer is related to the deposition time and the deposition temperature, that is, the deposition time and the deposition temperature will affect the growth rate of the thin film on the wafer. In the prior art, when the reaction gas is introduced, a fixed temperature is often maintained in the reaction chamber. Due to the poor thermal conductivity of the wafer, the thickness of the deposited film on the wafer is uneven. The film thickness deposited at the edge position of the wafer is often thicker, and the film thickness deposited at the center position of the wafer is thinner. After adopting steps S3 and S4 of this embodiment, when the reaction gas is introduced, the temperature is first cooled at a constant cooling rate, and then heated at a constant heating rate. In the entire process, the cooling stage and the heating stage of steps S3 and S4 offset each other in part of the temperature imbalance in the wafer, reduce the temperature difference of the wafer, and are conducive to improving the uniformity of the thickness of the deposited film on the wafer.
[0043] The thin film deposition method provided in this embodiment effectively reduces the temperature difference inside the furnace caused by the heating structure by lowering the temperature of the reaction chamber from the first temperature to the second temperature at a constant cooling rate, and raising the temperature of the reaction chamber from the second temperature to the third temperature at a constant heating rate; the strategy of dynamically adjusting the temperature makes the temperature at different positions on the wafer more uniform, thereby optimizing the temperature distribution of the entire wafer; and by utilizing the slow heat conduction characteristic of the wafer and accurately controlling the temperature change rate, the actual temperature difference inside and outside the wafer is effectively balanced.
[0044] The thin film deposition method provided in this embodiment significantly improves the in-wafer uniformity of the thin film through the above-mentioned temperature control strategy, thereby improving the overall quality and performance of the thin film, which is crucial to improving the performance and reliability of semiconductor devices.
[0045] In an optional embodiment, the constant cooling rate in step S3 is between 0.5°C / min and 2°C / min. During the entire process of performing step S3, the cooling rate is performed at a fixed value, for example, cooling at a fixed rate of 1.2°C / min. It is understandable that when different types of thin films are deposited on a wafer, the constant cooling rate used may be different. Optionally, the constant cooling rate in step S3 can be, for example, 0.5°C / min, 0.6°C / min, 0.7°C / min, 0.8°C / min, 0.9°C / min, 1.0°C / min, 1.1°C / min, 1.2°C / min, 1.3°C / min, 1.4°C / min, 1.5°C / min, 1.6°C / min, 1.7°C / min, 1.8°C / min, 1.9°C / min, 2°C / min, etc.
[0046] The constant heating rate in step S4 is between 0.5°C / min and 2°C / min. During the entire process of step S4, the heating rate is performed at a fixed value, for example, cooling at a fixed rate of 1.1°C / min. It is understandable that when different types of thin films are deposited on a wafer, the constant heating rate used may be different. Optionally, the constant heating rate in step S4 can be, for example, 0.5°C / min, 0.6°C / min, 0.7°C / min, 0.8°C / min, 0.9°C / min, 1.0°C / min, 1.1°C / min, 1.2°C / min, 1.3°C / min, 1.4°C / min, 1.5°C / min, 1.6°C / min, 1.7°C / min, 1.8°C / min, 1.9°C / min, 2°C / min, etc.
[0047] In the cooling process of step S3, since the heat conduction of the wafer is slow, therefore, in this stage, the center temperature of the wafer is slightly higher than its edge temperature. In the heating process of step S4, the heat conduction of the same wafer is slow, therefore, in this stage, the edge temperature of the wafer is slightly higher than its center temperature. The film deposition time of step S3 and step S4 is the same. After the cooling stage and the heating stage are combined, the temperature difference between the center of the whole wafer and its edge is relatively reduced. Therefore, in the process of step S3 and step S4, the reaction gas is introduced into the reaction chamber, and the thickness uniformity of the film deposited by the reaction gas on the wafer can be significantly improved.
[0048] In an optional embodiment, the value of the first temperature is greater than the value of the second temperature, and the difference between the first temperature and the second temperature is not greater than 35° C. Controlling the difference between the first temperature and the second temperature within a range of no more than 35° C. and cooling at a constant cooling rate is conducive to reducing the difference between the center position and the edge position inside the wafer, and further improving the uniformity of thin film deposition on the wafer.
[0049] In an optional embodiment, the total thickness of the thin film deposited on the wafer in step S3 and step S4 is between 500 angstroms and 700 angstroms. Optionally, the total thickness of the thin film deposited on the wafer in step S3 and step S4 can be, for example, 500 angstroms, 550 angstroms, 600 angstroms, 650 angstroms, 700 angstroms, etc. The smaller the thickness of the thin film deposited on the wafer, the more difficult it is to ensure the uniformity of the thin film. However, using the thin film deposition method of this embodiment, when the thickness of the thin film deposited on the wafer is between 500 angstroms and 700 angstroms, the difference in the non-uniformity of the thin film can be less than 1%, which significantly improves the uniformity of depositing thinner films on the wafer.
[0050] In an optional embodiment, the material of the thin film deposited on the wafer in step S3 and step S4 may be, for example, silicon nitride or silicon oxide.
[0051] In an optional embodiment, the first temperature is between 700°C and 1000°C. Optionally, the first temperature may be, for example, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, etc. The specific value selected for the first temperature is related to the material of the thin film deposited on the wafer and the thickness of the thin film. Compared with the constant temperature used in the process of thin film deposition by introducing reaction gas in the prior art, the first temperature used in this embodiment is relatively high.
[0052] In an optional embodiment, the third temperature is 1% to 1.5% lower than the first temperature. Since the constant cooling rate is greater than the constant heating rate, when the same process time is used in step S3 and step S4, the value of the third temperature is smaller than the value of the first temperature. By setting the parameters in step S3 and step S4, the uniformity of the deposited film on the wafer can be significantly improved. Optionally, the value of the third temperature lower than the first temperature can be, for example, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, etc.
[0053] In an optional embodiment, the initial temperature is between 400°C and 800°C. Optionally, the initial temperature may be, for example, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, etc. This temperature is the standby temperature of the reaction chamber. Similarly, when different types of furnace bodies and different materials of deposited films are selected, the initial temperature in the reaction chamber may be different. As long as the values of the first temperature, the second temperature, the third temperature, the constant cooling rate and the constant heating rate are within the range provided in this embodiment, the uniformity of the film deposited on the wafer can be improved.
[0054] In an optional embodiment, the heating rate when the temperature of the reaction chamber is raised from the initial temperature to the first temperature is between 5°C / min and 10°C / min. Optionally, the heating rate when the temperature of the reaction chamber is raised from the initial temperature to the first temperature can be, for example, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, etc. This embodiment does not make specific requirements on the heating rate, and its value is related to the furnace model used, the initial temperature, and the process time required to raise the temperature from the initial temperature to the first temperature.
[0055] The wafer is placed on the wafer boat and enters the furnace process program. The entire process program includes steps such as raising the wafer boat, heating, side leakage, pipeline pre-flow, film growth, pipeline emptying, cooling, and wafer boat. The above steps of this embodiment only record the steps that have a greater impact on the uniformity of the deposited film, and the more conventional steps are not all recorded.
[0056] A 500 angstrom thick silicon nitride film was deposited on a wafer using the thin film deposition method provided in this embodiment (specifically, the constant cooling rate was 1.2°C / min, and the constant heating rate was 1.1°C / min), and a 500 angstrom thick silicon nitride film was deposited on a wafer using the process method in the prior art (specifically, the temperature in the same temperature zone remained unchanged during the deposition stage). The 500 angstrom thick silicon nitride films obtained by the two methods were subjected to film uniformity tests. The test methods are commonly used in the art. The test results are shown in FIG. Figure 2 As shown, it can be seen that the in-plane non-uniformity values of different positions of the silicon nitride film obtained by the process method in the prior art are relatively high, while the in-plane non-uniformity values of different positions of the silicon nitride film obtained by the thin film deposition method of this embodiment are within 1%. Therefore, the uniformity of the film obtained by the thin film deposition method of this embodiment can be significantly improved.
[0057] Embodiment 2
[0058] This embodiment also provides a thin film deposition method, such as Figure 3 As shown, the thin film deposition method comprises the following steps:
[0059] S1, placing the wafer to be coated on a wafer boat and sending it into a reaction chamber, where the reaction chamber has an initial temperature;
[0060] S2, raising the temperature of the reaction chamber to a first temperature;
[0061] S3, lowering the temperature of the reaction chamber from the first temperature to the second temperature at a constant cooling rate, and introducing a reaction gas during the cooling process, so that the reaction gas deposits a thin film on the wafer;
[0062] S4, raising the temperature of the reaction chamber from the second temperature to the third temperature at a constant heating rate, and introducing a reaction gas during the heating process, so that the reaction gas continues to deposit a thin film on the wafer;
[0063] S5, repeat steps S2 to S4 for a preset number of times;
[0064] S6. Lowering the temperature of the reaction chamber from the third temperature to the initial temperature.
[0065] The difference between this embodiment and the first embodiment is that the thickness of the film deposited in this embodiment is at least twice the thickness of the film deposited in the first embodiment, therefore, steps S2 to S4 need to be repeated for a preset number of times, which depends on the multiple of the thickness of the film deposited in this embodiment and the thickness of the film deposited in the first embodiment. When repeating step S2, the temperature of the reaction chamber needs to be further increased from the third temperature of step S4 to the first temperature, and no reaction gas is passed during this process.
[0066] The thin film deposition method provided in this embodiment is also beneficial for balancing the actual temperature difference inside and outside the wafer, optimizing the temperature distribution of the entire wafer, improving the uniformity of the deposited film, improving the overall quality and performance of the film, and improving the performance and reliability of semiconductor devices.
[0067] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.
Claims
1. A thin film deposition method, characterized in that: The following steps are involved: S1, placing the wafer to be coated on a wafer boat and sending it into a reaction chamber, wherein the reaction chamber has an initial temperature; S2, raising the temperature of the reaction chamber to a first temperature; S3, lowering the temperature of the reaction chamber from the first temperature to a second temperature at a constant cooling rate, and introducing a reaction gas during the cooling process, so that the reaction gas deposits a thin film on the wafer; S4, raising the temperature of the reaction chamber from the second temperature to a third temperature at a constant heating rate, and introducing a reaction gas during the heating process, so that the reaction gas continues to deposit a thin film on the wafer; S5, lowering the temperature of the reaction chamber from the third temperature to the initial temperature; Wherein, the constant cooling rate is greater than the constant heating rate.
2. The thin film deposition method according to claim 1, characterized in that: The constant cooling rate in step S3 is between 0.5°C / min and 2°C / min.
3. The thin film deposition method according to claim 1, characterized in that: The difference between the first temperature and the second temperature is no greater than 35°C.
4. The thin film deposition method according to claim 1, characterized in that: The constant heating rate in step S4 is between 0.5°C / min and 2°C / min.
5. The thin film deposition method according to claim 1, characterized in that: The total thickness of the thin film deposited on the wafer in step S3 and step S4 is between 500 angstroms and 700 angstroms.
6. The thin film deposition method according to claim 1, characterized in that: The material of the thin film deposited on the wafer in step S3 and step S4 is silicon nitride or silicon oxide.
7. The thin film deposition method according to claim 1, characterized in that: The first temperature is between 700°C and 1000°C.
8. The thin film deposition method according to claim 1, characterized in that: The third temperature is 1% to 1.5% lower than the first temperature.
9. The thin film deposition method according to claim 1, characterized in that: After step S4 and before step S5, the method further includes repeating steps S2 to S4 for a preset number of times.
10. The thin film deposition method according to claim 1, characterized in that: The initial temperature is between 400° C. and 800° C.; and the heating rate when the temperature of the reaction chamber is raised from the initial temperature to the first temperature is between 5° C. / min and 10° C. / min.