A semiconductor wafer light heating control method, medium and system

Abstract

The application discloses a kind of semiconductor wafer light heating control method, medium and system, method includes the following steps: standard heating curve of wafer under different heating power is obtained in advance, and the standard temperature rise rate of linear heating section under corresponding heating power is obtained according to standard heating curve under different heating power;Wherein wafer is heated by using non-contact heat source of light heating;When wafer is heated, the initial temperature, target temperature and heating power of wafer are obtained;The standard heating curve of wafer is obtained according to the heating power thereof, and then the standard temperature rise rate of linear heating section is obtained according to the standard heating curve, and then the corresponding heating time is obtained according to the standard temperature rise rate, initial temperature and target temperature, to heat wafer for corresponding heating time.The application has the advantages of simple operation, precise control and the like.

Description

Technical Field

[0001] This invention relates primarily to the field of semiconductor technology, specifically to a method, medium, and system for controlling optical heating of semiconductor wafers. Background Technology

[0002] The development of semiconductor integrated circuit manufacturing processes has placed higher demands on the performance of semiconductor manufacturing equipment and the methods for controlling manufacturing processes. Ion implanters are the core doping equipment in semiconductor device manufacturing. When ions are implanted into semiconductors, damage to the semiconductor lattice structure occurs. Therefore, post-implantation annealing is necessary to eliminate this damage. For materials such as silicon carbide, which have high density and low impurity diffusion coefficients, diffusion methods similar to those used for silicon present significant challenges. Room temperature implantation methods suffer from low impurity activation rates and difficulty in defect recovery. Therefore, it is necessary to heat the wafer to a specific temperature before implantation to control implantation defects and ensure implantation uniformity.

[0003] To reduce damage caused by thermal expansion from direct heating of wafers on high-temperature chucks, preheating devices are typically used to preheat the wafers to minimize their expansion deformation. These heating processes directly impact product quality in related manufacturing processes, and infrared or laser heating devices are commonly used to achieve this. However, because silicon and silicon carbide wafers have high transmittance in the infrared band, non-contact infrared measurement methods are prone to interference with wafer temperature measurement due to the infrared signal from the heating source directly or after reflection from surrounding devices. Contact measurements using temperature probes may damage the wafer itself. Therefore, feedback control based on wafer temperature measurement presents significant technical challenges. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the present invention provides a simple and precise method, medium, and system for controlling the light heating of semiconductor wafers.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A method for controlling optical heating of a semiconductor wafer, comprising the following steps: Standard heating curves of the wafer at different heating powers are obtained in advance, and the standard temperature rise rate of the linear heating section at the corresponding heating power is obtained based on the standard heating curves at different heating powers; wherein the wafer is heated by using a non-contact heat source of light heating. During wafer heating, the initial temperature, target temperature, and heating power of the wafer are obtained; The standard heating curve of the wafer is obtained based on the heating power. Then, the standard temperature rise rate of the linear heating section is obtained based on the standard heating curve. Finally, the corresponding heating time is obtained based on the standard temperature rise rate, the initial temperature, and the target temperature, and the wafer is heated for the corresponding time.

[0006] Preferably, the process of obtaining standard heating curves of the wafer under different heating powers in advance is as follows: The wafer is heated from the initial temperature T0. After the heating process, it reaches temperature T1 at time t1. After that, the heating power of the heat source is constant, and it enters a linear heating process, reaching temperature T2 at time t2. After time t2, the heat source is turned off, and the heating gradually slows down until the highest temperature T3 is reached at time t3. After that, the wafer temperature gradually decreases, completing the heating process, and thus obtaining the standard heating curve under the corresponding heating power.

[0007] Preferably, the portion of the standard heating curve between time t1 and t2 is taken as the linear heating segment.

[0008] Preferably, the standard temperature rise rate of the linear heating section is (T2–T1) / (t2-t1).

[0009] Preferably, the specific process for obtaining the heating time is as follows: The new initial temperature of the wafer becomes T0′, and the new target temperature becomes T3′. Therefore, the overall heating time needs to be adjusted. The specific adjustment amount is Δt=((T0-T0′)+(T3′-T3)) / ((T2–T1) / (t2-t1);The new heating time is t3′=t3+Δt.

[0010] Preferably, the light heating method includes visible light, infrared heat lamps, or lasers.

[0011] Preferably, the heating power is adjusted by controlling the operating current or operating voltage of the heating unit or the impedance level of the heating circuit.

[0012] Preferably, the heating power is adjusted by controlling the peak value, duty cycle, or average value of the operating current or operating voltage of the heating unit.

[0013] The present invention also discloses a computer-readable storage medium having a computer program stored thereon, the computer program performing the steps of the method described above when run by a processor.

[0014] The present invention further discloses a semiconductor wafer optical heating control device, including a memory and a processor connected to each other, wherein the memory stores a computer program, and the computer program executes the steps of the method described above when run by the processor.

[0015] Compared with the prior art, the advantages of the present invention are as follows: This invention obtains a standard heating curve for wafers based on prior test data, and uses the linear temperature evolution period in the standard heating curve to control the heating of the wafer to reach a specific process temperature by adjusting the heating time. Because wafer heating is controlled by timing, the wafer photothermal heating process is simple and precisely controlled.

[0016] This invention is applied to temperature control in high-temperature ion implanters and annealing equipment where wafers need to be photo-heated to high temperatures for related processes. By pre-testing standard heating curves at various heating powers and referencing the temperature rise rate of the linear heating portion, parameters such as the required heating time at different starting and target temperatures can be deduced by adjusting the total heating time, achieving temperature control for heating processes with target temperatures exceeding 600°C. The heating rate can be further adjusted by regulating the output power of the heating device. This method avoids controlling the changes in the heating device's output power during power-on and power-off processes, achieving simple and accurate control of the heating process by controlling the linear heating portion. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of how a non-contact heat source using photothermal heating heats a wafer in this invention.

[0018] Figure 2 This is a graph of the standard heating curve in this invention in an embodiment.

[0019] Figure 3 This is a flowchart of the control method of the present invention in an embodiment. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 3 As shown, the semiconductor wafer optical heating control method provided in this embodiment of the invention includes the following steps: Standard heating curves of the wafer at different heating powers are obtained in advance, and the standard temperature rise rate of the linear heating section at the corresponding heating power is obtained based on the standard heating curves at different heating powers; wherein the wafer is heated by using a non-contact heat source of light heating. During wafer heating, the initial temperature, target temperature, and heating power of the wafer are obtained; The standard heating curve of the wafer is obtained based on the heating power. Then, the standard temperature rise rate of the linear heating section is obtained based on the standard heating curve. Finally, the corresponding heating time is obtained based on the standard temperature rise rate, the initial temperature, and the target temperature, and the wafer is heated for the corresponding time.

[0022] This invention obtains a standard heating curve for wafers based on prior test data, and uses the linear temperature evolution period in the standard heating curve to control the heating of the wafer to reach a specific process temperature by adjusting the heating time. Because wafer heating is controlled by timing, the wafer photothermal heating process is simple and precisely controlled.

[0023] Specifically, a non-contact heat source, including but not limited to visible light, infrared lamps, or lasers, is used to test-heat a wafer in a vacuum or atmospheric state within a heating device. A wafer with temperature measurement capabilities or other measuring devices is used to record a standard heating curve of the wafer under specific heating conditions. During this process, the heating device needs to reach a stable operating state and maintain it for a certain period. The main parameters to be recorded are the total heating time and the operating power of the heating device, which can be adjusted by controlling parameters such as the operating voltage or current of the heating device.

[0024] Specifically, the process for obtaining the standard heating curve is as follows: The wafer is heated from an initial temperature T0. As the heating device gradually starts up, it first undergoes an accelerated heating process, reaching temperature T1 at time t1. Afterward, as the heating power of the heat source reaches a stable level, and the heating power of the light source is much greater than the heat dissipation power of the wafer, the wafer enters a linear heating process and reaches temperature T2 at time t2. After time t2, as the heat source is gradually turned off, the heating gradually slows down, reaching the maximum temperature T3 at time t3. The wafer temperature then gradually decreases, ultimately yielding the standard heating curve for the corresponding heating power.

[0025] By repeating the above method, standard heating curves can be obtained under different heat source heating powers.

[0026] Based on the obtained standard heating curve, the heating process is controlled. For a specific standard heating curve, referring to the linear heating process, the temperature rise rate of the process can be calculated as (T2–T1) / (t2–t1) based on the time length t2–t1 and the temperature difference T2–T1. From this, the necessary adjustments due to changes in the initial and target temperatures can be calculated. Assuming the new initial temperature becomes T0′ and the target temperature becomes T3′, the overall heating time needs to be corrected from t3. The correction amount for the heating time is Δt = ((T0–T0′) + (T3′–T3)) / ((T2–T1) / (t2–t1)). The new heating time is t3′ = t3 + Δt, meaning that by changing the heating time Δt based on the standard heating curve heating time t3, the final target temperature can be reached at the new target temperature T3′.

[0027] like Figure 1As shown, the test heating can be performed in an offline testing environment or on a heating device on a machine. The heating environment can be a vacuum or atmospheric environment. When the heating device is in operation, it uses light, including but not limited to visible light, infrared heat lamps, or lasers, to heat the wafer inside the heating device directly or through an optical window. During test heating, a wafer equipped with a temperature measurement device, including but not limited to a wafer with a temperature measurement sensor that transmits signals wirelessly or wiredly, is used to determine a standard heating profile.

[0028] The heating device can regulate the heating process by adjusting the power of the output light. The adjustment methods include, but are not limited to, controlling characteristic parameters such as the peak value, duty cycle, and average value of electrical signals such as working current and working voltage, or adjusting the impedance level of the heating circuit to achieve the purpose of controlling the output power of the heating light generator.

[0029] Building upon the above-mentioned ability to control the target heating temperature at a specific heating power, if it is necessary to control the heating rate, the heating power of the heat source can be changed to adjust the standard heating curve and obtain a new heating rate, thus achieving the corresponding heating target control. For a specific heating rate, it can be obtained by extrapolation or interpolation approximation using standard heating curves at different heating powers.

[0030] Based on the aforementioned control methods, their applicability in ensuring control accuracy is further standardized. Specifically, the standard temperature rise curve used to calculate heating control exhibits a time-temperature curve portion with good linearity during the heating process. By altering the overall heating time, the control over the power-on and power-off processes is effectively avoided; instead, the heating process is controlled by regulating the linear heating portion.

[0031] This invention is applied to temperature control in high-temperature ion implanters and annealing equipment where wafers need to be photo-heated to high temperatures for related processes. By pre-testing standard heating curves at various heating powers and referencing the temperature rise rate of the linear heating portion, parameters such as the required heating time at different starting and target temperatures can be deduced by adjusting the total heating time, achieving temperature control for heating processes with target temperatures exceeding 600°C. The heating rate can be further adjusted by regulating the output power of the heating device. This method avoids controlling the changes in the heating device's output power during power-on and power-off processes, achieving simple and accurate control of the heating process by controlling the linear heating portion.

[0032] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when run by a processor, performs the steps of the method described above. This invention further discloses a semiconductor wafer optical heating control system, including a memory and a processor interconnected, wherein the memory stores a computer program that, when run by a processor, performs the steps of the method described above. The medium and system of this invention, corresponding to the methods described above, also possess the advantages described above.

[0033] The present invention can implement all or part of the processes in the methods of the above embodiments, or it can be implemented by hardware related to computer program instructions. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of the above method embodiments. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium includes: any entity or device capable of carrying computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. The memory is used to store computer programs and / or modules. The processor implements various functions by running or executing the computer programs and / or modules stored in the memory, and by calling data stored in the memory. The memory may include high-speed random access memory, as well as non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital (SD) cards, flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0034] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for controlling optical heating of a semiconductor wafer, characterized in that, Including the following steps: Standard heating curves of the wafer at different heating powers are obtained in advance, and the standard temperature rise rate of the linear heating section at the corresponding heating power is obtained based on the standard heating curves at different heating powers; wherein the wafer is heated by using a non-contact heat source of light heating. During wafer heating, the initial temperature, target temperature, and heating power of the wafer are obtained; The standard heating curve of the wafer is obtained based on the heating power of the wafer. Then, the standard temperature rise rate of the linear heating section is obtained based on the standard heating curve. Finally, the corresponding heating time is obtained based on the standard temperature rise rate, the initial temperature and the target temperature, and the wafer is heated for the corresponding heating time. The process of obtaining standard heating curves of wafers under different heating powers in advance is as follows: The wafer is heated from the initial temperature T0. After the heating process, it reaches temperature T1 at time t1. After that, the heating power of the heat source is constant, and it enters a linear heating process, reaching temperature T2 at time t2. After time t2, the heat source is turned off, and the heating gradually slows down until the highest temperature T3 is reached at time t3. After that, the wafer temperature gradually decreases, completing the heating process, and thus obtaining the standard heating curve under the corresponding heating power. The portion of the standard heating curve between time t1 and t2 is taken as the linear heating segment; The specific process for obtaining the heating time is as follows: The new initial temperature of the wafer becomes T0′, and the new target temperature becomes T3′. Therefore, the overall heating time needs to be adjusted. The specific adjustment amount is Δt=((T0-T0′)+(T3′-T3)) / ((T2–T1) / (t2-t1);The new heating time is t3′=t3+Δt.

2. The semiconductor wafer optical heating control method according to claim 1, characterized in that, The standard temperature rise rate of the linear heating section is obtained as (T2–T1) / (t2-t1).

3. The semiconductor wafer optical heating control method according to any one of claims 1-2, characterized in that, Light heating methods include visible light, infrared heat lamps, or lasers.

4. The semiconductor wafer optical heating control method according to claim 3, characterized in that, The heating power is adjusted by controlling the operating current or voltage of the heating unit or the impedance level of the heating circuit.

5. The semiconductor wafer optical heating control method according to claim 4, characterized in that, Specifically, the heating power is adjusted by controlling the peak value, duty cycle, or average value of the operating current or operating voltage of the heating unit.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, The computer program, when run by a processor, performs the steps of the method as described in any one of claims 1-5.

7. A semiconductor wafer optical heating control device, comprising a memory and a processor interconnected, wherein the memory stores a computer program, characterized in that, The computer program, when run by a processor, performs the steps of the method as described in any one of claims 1-5.

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