A control method, device and system for wafer temperature

Abstract

The application provides a wafer temperature control method, device and system, the method comprising: monitoring the back helium flow, the back helium flow is used to indicate the adsorption force between the electrostatic chuck and the wafer; in the case where the adsorption force is inconsistent with the standard adsorption force, adjusting the adsorption force so that the adsorption force is consistent with the standard adsorption force, and the consistency of the adsorption force and the standard adsorption force is used to indirectly reflect the consistency of the temperature between the wafers. In the scheme, the fitting degree of the wafer and the ESC is measured by monitoring the back helium flow, the heat transfer between the ESC and the wafer is ensured to always remain within the standard range, and then the temperature consistency between the wafers and the wafer temperature uniformity are ensured.

Description

Technical Field

[0001] This invention relates to the field of semiconductor equipment control manufacturing, and specifically to a method, apparatus, and system for controlling wafer temperature. Background Technology

[0002] In semiconductor manufacturing processes, the electrostatic chuck (ESC) is a core component in equipment used for etching, deposition, and ion implantation. Its main functions include supporting the wafer, conducting radio frequency energy, and controlling wafer temperature through a backside helium cooling system. The uniformity and consistency of wafer temperature directly affect key process parameters such as etching rate, critical dimension (CD), etching profile, uniformity, and selectivity, thereby determining product yield.

[0003] In existing technologies, to achieve precise control of wafer temperature, temperature sensors and heating / cooling actuators are typically deployed simultaneously in each temperature control zone of the electrostatic chuck. A multi-channel back-blown inert gas supply module is used to independently adjust the back helium pressure of each zone. The process power signal is then acquired in real time through a process power monitoring interface. Multiple computing units in the dynamic compensation controller work together to calculate the thermal compensation amount for each zone, and finally output the corresponding heating / cooling power command and back helium pressure command, which are then executed quickly by the actuator.

[0004] However, the aforementioned prior art has the following drawbacks: Complex hardware structure and high cost: A large number of temperature sensors, heating / cooling units and multi-channel independent pressure supply modules need to be integrated into the ESC, resulting in a complex ESC structure, high manufacturing cost and high maintenance difficulty.

[0005] Incomplete temperature control: This technology can only guarantee the uniformity of temperature at the ESC body, but in reality, the heat transfer efficiency between the ESC and the wafer is the key factor determining the actual wafer temperature. Uniform temperature at the ESC end does not guarantee uniform temperature at the wafer end because the thermal contact resistance between different wafers and the ESC varies.

[0006] Lack of universality: This solution requires recalibration and configuration for different processes and equipment, making it difficult to promote and apply universally across various etching equipment.

[0007] Differences between wafers are not taken into account: Due to differences in back-side film, morphology, warpage, etc., different wafers have different actual contact states with ESC, resulting in changes in thermal contact resistance, which in turn causes temperature inconsistencies between wafers. Existing technology has failed to effectively compensate for this difference.

[0008] Therefore, the industry urgently needs a low-cost, simple, and universally applicable technical solution that can truly guarantee temperature consistency between wafers and temperature uniformity on the same wafer, thereby improving process consistency and product yield. Summary of the Invention

[0009] The purpose of this invention is to provide a method, device, and system for controlling wafer temperature. This invention measures the degree of adhesion between the wafer and the ESC by monitoring the back helium flow rate, ensuring that the heat transfer between the ESC and the wafer is always kept within the standard range, thereby ensuring the temperature consistency and uniformity between wafers.

[0010] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, this application provides a control system for wafer temperature, the method comprising: Monitor the back helium flow rate, which is used to indicate the adsorption force between the electrostatic chuck and the wafer; If the adsorption force is inconsistent with the standard adsorption force, the adsorption force is adjusted so that the adsorption force is consistent with the standard adsorption force. The consistency of the adsorption force with the standard adsorption force is used to indirectly reflect the temperature consistency between wafers.

[0011] In some embodiments, adjusting the adsorption force includes: Adjust the high voltage HV, which is positively correlated with the adsorption force.

[0012] In some embodiments, the back helium flow rate is positively correlated with the adsorption force.

[0013] Secondly, this application provides a wafer temperature control device, the device comprising: The monitoring module is used to monitor the back helium flow rate, which is used to indicate the adsorption force between the electrostatic chuck and the wafer. The adjustment module is used to adjust the adsorption force when the adsorption force is inconsistent with the standard adsorption force, so that the adsorption force is consistent with the standard adsorption force. The consistency of the adsorption force with the standard adsorption force is used to indirectly reflect the temperature consistency between wafers.

[0014] Thirdly, this application provides a control system for wafer temperature, the system comprising: A monitoring unit is used to monitor the back helium flow rate, which is used to indicate the adsorption force between the electrostatic chuck and the wafer; A voltage unit is used to adjust the adsorption force when the adsorption force is inconsistent with the standard adsorption force, so that the adsorption force is consistent with the standard adsorption force. The consistency of the adsorption force with the standard adsorption force is used to indirectly reflect the temperature consistency between wafers.

[0015] In some embodiments, the voltage unit is further configured to adjust the HV voltage, which is positively correlated with the adsorption force.

[0016] Fourthly, this application provides a wafer temperature control program for executing the wafer temperature control method described above.

[0017] Fifthly, this application provides a semiconductor device for performing the wafer temperature control method described above.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: By indirectly reflecting the actual heat transfer state (thermal contact resistance) between the ESC and the wafer through the back helium flow rate, the key factors affecting the wafer temperature can be directly controlled, rather than just focusing on the temperature of the ESC itself. This fundamentally ensures the temperature consistency between wafers and the temperature uniformity on the same wafer. Attached Figure Description

[0019] Figure 1 This is a flowchart of a wafer temperature control method provided in an embodiment of this application; Figure 2 This is a flowchart of a wafer temperature control method provided in an embodiment of this application; Figure 3 This is a structural block diagram of a wafer temperature control device provided in an embodiment of this application. Detailed Implementation

[0020] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0021] In semiconductor etching and other processes requiring ESC (Extractable Solids), the strength of the ESC's adhesion to the wafer is a key variable that directly affects process performance and results. Its physical mechanism is as follows: 1. Relationship between back helium flow rate and adsorption force For a given process recipe, the back helium pressure remains constant. Back helium gas enters the tiny gap (typically a few micrometers to tens of micrometers) between the wafer and the ESC through micropores on the ESC surface. When the ESC's adhesion to the wafer is weak, the gap between the wafer and the ESC is larger, the flow resistance of the back helium gas is lower, and the actual back helium flow rate is higher. Conversely, when the ESC's adhesion to the wafer is strong, the wafer is pressed more tightly against the ESC surface, the gap becomes smaller, the flow resistance increases, and the actual back helium flow rate is lower.

[0022] Therefore, under the condition of constant back helium pressure, the magnitude of back helium flow rate can indirectly reflect the magnitude of the ESC's adsorption force on the wafer.

[0023] 2. Relationship between adsorption force and thermal contact resistance Heat transfer between the ESC and the wafer occurs primarily through two pathways: direct contact conduction between the wafer and the bumps on the ESC surface; and convection and conduction of back helium gas within the gaps. The strength of the adhesion force directly affects the bonding strength between the wafer and the ESC surface. The greater the adsorption force, the tighter the contact between the wafer and the ESC surface, the larger the actual contact area, the smaller the thermal contact resistance, and the better the heat transfer efficiency. The weaker the adsorption force, the larger the gap between the wafer and the ESC surface, the greater the thermal contact resistance, and the lower the heat transfer efficiency.

[0024] Therefore, the magnitude of the adsorption force directly affects the thermal contact resistance between the ESC and the wafer, and thus affects the actual temperature of the wafer.

[0025] 3. The Influence of Wafer Temperature on Processing During plasma etching, the plasma continuously injects heat into the wafer. If the wafer temperature is too high, the etching rate accelerates, potentially leading to smaller critical dimensions and uncontrolled etching profiles. Conversely, if the wafer temperature is too low, the etching rate slows down, potentially resulting in incomplete etching and larger critical dimensions. Uneven temperature distribution can cause inconsistent etching rates in different areas of the wafer, leading to problems such as uneven linewidth and decreased selectivity.

[0026] Therefore, ensuring temperature consistency between different wafers and within the same wafer is crucial for guaranteeing process stability and product yield. Based on this, embodiments of this application provide a method for controlling wafer temperature, such as... Figure 1 As shown, the method includes: Step 110: Monitor back helium flow rate; In some embodiments, the back helium flow rate is used to indicate the adhesion force between the electrostatic chuck and the wafer.

[0027] Back helium flow rate is positively correlated with adsorption force. Generally, the higher the back helium flow rate, the higher the adsorption force required between the electrostatic chuck and the wafer. By monitoring the back helium flow rate, the required adsorption force between the electrostatic chuck and the wafer can be determined.

[0028] In some embodiments, prior to step 110, before the semiconductor device begins operation, a standard back helium flow rate is pre-tested to obtain a standard back helium flow rate value. Optionally, the standard back helium flow rate value is obtained under standard process conditions. The standard back helium flow rate value corresponds to a standard adsorption force.

[0029] Furthermore, during the operation of the semiconductor equipment, the back helium flow rate is monitored to indirectly determine whether the adsorption force is consistent with the standard adsorption force. If the adsorption force is consistent with the standard adsorption force, the wafer temperature consistency is considered high, and no adjustment is required. Alternatively, step 110 can be continued to monitor the back helium flow rate. If the adsorption force is inconsistent with the standard adsorption force, step 120 can be continued.

[0030] Step 120: If the adsorption force is inconsistent with the standard adsorption force, adjust the adsorption force to make it consistent with the standard adsorption force.

[0031] In some embodiments, the adsorption force is consistent with the standard adsorption force to indirectly reflect the temperature consistency between wafers.

[0032] In some embodiments, the adsorption force is positively correlated with the HV voltage. The higher the voltage, the stronger the adsorption force. If the adsorption force is inconsistent with the standard adsorption force, it is considered that there is a deviation between the current back helium flow rate and the standard back helium flow rate. In this case, the deviation δ between the current back helium flow rate and the standard back helium flow rate is calculated. For example, δ = Q1 - Q0, where Q1 represents the current back helium flow rate and Q0 represents the standard back helium flow rate.

[0033] In some embodiments, if the current back helium flow rate is equal to the standard back helium flow rate, or if δ = 0, the current adsorption force is considered to be consistent with the standard adsorption force, and therefore no adjustment of the HV voltage is required. If the current back helium flow rate is greater than the standard back helium flow rate, or if δ > 0, the current adsorption force is considered to be greater than the standard adsorption force, and therefore the HV voltage needs to be reduced. If the current back helium flow rate is less than the standard back helium flow rate, or if δ > 0, the current adsorption force is considered to be greater than the standard adsorption force, and therefore the HV voltage needs to be reduced.

[0034] like Figure 2 As shown in the embodiments of this application, the back helium flow rate can measure the magnitude of the adsorption force, which in turn indirectly affects the wafer temperature. Therefore, in order to ensure the consistency of the wafer temperature, the magnitude of the adsorption force can be controlled, and the magnitude of the adsorption force can be indirectly adjusted by the HV voltage.

[0035] In this embodiment, through real-time monitoring and feedback adjustment, the thermal contact resistance variation caused by differences in back-side film, morphology, warpage, etc. of different wafers can be adaptively compensated, ensuring that each wafer can obtain consistent heat transfer conditions.

[0036] By maintaining consistent adsorption force and heat transfer state, problems such as etching rate changes, critical dimension drift, and etching profile distortion caused by temperature fluctuations are effectively suppressed, significantly improving process consistency and product yield.

[0037] In some embodiments, based on the above-described wafer temperature control method, if the back helium flow rate of a wafer deviates significantly from the standard back helium flow rate, or is interpreted as exceeding the allowable adjustment range of the HV voltage, it indicates that the heat exchange between the wafer and the ESC is too large or too small, which will indirectly affect process stability and increase the probability of product defects. In this case, the wafer is automatically marked as a high-risk product wafer, and an early warning message is generated. By marking products with a high probability of defects through abnormal back helium flow rate, online quality monitoring of the process is achieved, which helps to promptly detect process anomalies and wafer defects. This application also provides a wafer temperature control device, such as... Figure 3 As shown, the device includes: Monitoring module 310 is used to monitor the back helium flow rate.

[0038] Back helium flow rate is used to indicate the adhesion force between the electrostatic chuck and the wafer.

[0039] The adjustment module 320 is used to adjust the adsorption force when the adsorption force is inconsistent with the standard adsorption force, so that the adsorption force is consistent with the standard adsorption force.

[0040] Adsorption force consistent with standard adsorption force is used to indirectly reflect temperature consistency between wafers.

[0041] Alternatively, it can be understood that the device is used to perform the aforementioned method for controlling wafer temperature.

[0042] In this embodiment of the application, the above-mentioned method for controlling wafer temperature can be applied to a semiconductor device. The semiconductor device monitors the back helium flow rate to determine whether there is a change in the adsorption force. If the adsorption force differs from the standard value, the adsorption force is indirectly adjusted by the HV voltage, thereby indirectly ensuring that the wafer temperature is consistent.

[0043] Optionally, the semiconductor device may be an etching device, a resist stripping device, or other device that may apply the above-described methods for controlling wafer temperature. In this embodiment of the application, a control system for wafer temperature is also provided, the system comprising: The monitoring unit is used to monitor the back helium flow rate.

[0044] Back helium flow rate is used to indicate the adhesion force between the electrostatic chuck and the wafer.

[0045] The voltage unit is used to adjust the adsorption force when it is inconsistent with the standard adsorption force, so that the adsorption force is consistent with the standard adsorption force.

[0046] Adsorption force consistent with standard adsorption force is used to indirectly reflect temperature consistency between wafers.

[0047] The voltage unit is also used to adjust the HV voltage, which is positively correlated with the adsorption force.

[0048] Back helium flow rate is positively correlated with adsorption force. The applicant declares that the above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for controlling wafer temperature, characterized in that, The method includes: Monitor the back helium flow rate, which is used to indicate the adsorption force between the electrostatic chuck and the wafer; If the adsorption force is inconsistent with the standard adsorption force, the adsorption force is adjusted so that the adsorption force is consistent with the standard adsorption force. The consistency of the adsorption force with the standard adsorption force is used to indirectly reflect the temperature consistency between wafers.

2. The wafer temperature control method as described in claim 1, characterized in that, The adjustment of the adsorption force includes: Adjust the high voltage HV, which is positively correlated with the adsorption force.

3. The method for controlling wafer temperature as described in claim 1 or 2, characterized in that, The back helium flow rate is positively correlated with the adsorption force.

4. A device for controlling wafer temperature, characterized in that, The device includes: The monitoring module is used to monitor the back helium flow rate, which is used to indicate the adsorption force between the electrostatic chuck and the wafer. The adjustment module is used to adjust the adsorption force when the adsorption force is inconsistent with the standard adsorption force, so that the adsorption force is consistent with the standard adsorption force. The consistency of the adsorption force with the standard adsorption force is used to indirectly reflect the temperature consistency between wafers.

5. A control system for wafer temperature, characterized in that, The system includes: A monitoring unit is used to monitor the back helium flow rate, which is used to indicate the adsorption force between the electrostatic chuck and the wafer; A voltage unit is used to adjust the adsorption force when the adsorption force is inconsistent with the standard adsorption force, so that the adsorption force is consistent with the standard adsorption force. The consistency of the adsorption force with the standard adsorption force is used to indirectly reflect the temperature consistency between wafers.

6. The wafer temperature control system as described in claim 5, characterized in that, The voltage unit is also used to adjust the HV voltage, which is positively correlated with the adsorption force.

7. A control program for wafer temperature, characterized in that, The program is used to execute the wafer temperature control method as described in claims 1 to 3.

8. A semiconductor device, characterized in that, The semiconductor device is used to perform the wafer temperature control method as described in claims 1 to 3.

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