Ion implantation apparatus and ion implantation method

Abstract

This invention provides an ion implantation apparatus and an ion implantation method. By incorporating a cooling unit and a closed-loop automatic controller within the ion implantation apparatus, the wafer stage is cooled in real-time by adjusting the flow rate of the coolant flowing through the cooling unit. This maintains the target operating temperature of the wafer stage throughout the wafer placement and ion implantation process, avoiding waiting and interruptions caused by temperature rise. Simultaneously, the ion implantation method employs parallel wafer stage cooling and machine beam adjustment, completing pre-cooling of the wafer stage during machine beam adjustment. This effectively shortens the single-wafer operation cycle, improves throughput and continuity, and increases equipment uptime. Furthermore, precise temperature control avoids frequent wafer transfers and temperature fluctuations, reducing collisions, wafer drop, and particle defects, thus improving product yield and enhancing product performance stability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to an ion implantation device and an ion implantation method. Background Technology

[0002] As devices become smaller and smaller, the impact of different implantation materials and the resulting surface smoothness during ion implantation becomes increasingly significant, especially the implantation temperature, which is crucial for improving product performance. The shrinking device size coupled with ever-increasing performance requirements results in shallower junction depths. To maintain power consumption, it's necessary to reduce the resistance of the source, drain, and lightly doped drain, but this contradicts the shallower junction depth, as shallower junction depth leads to increased resistance. Therefore, reducing resistance can only be achieved by adjusting the doping concentration, leading to a gradual increase in the doping concentration of the lightly doped drain. However, higher concentrations introduce more lattice defects. To address these issues, cryogenic implantation was introduced. During cryogenic implantation, the lattice self-repair process becomes extremely slow. In this case, the amorphous state is generated more rapidly, and the amorphous layer has fewer lattice voids, effectively blocking the rapid penetration of implanted atoms, thus significantly reducing lattice defects beneath the amorphous layer after annealing.

[0003] However, in practical applications, we have found that the low number of work-in-process (WIP) and the high number of defects in the cryogenic implantation method restrict the improvement of production capacity and product stability. Before cryogenic implantation, the platen needs to be cooled from room temperature to the required implantation temperature. This process relies on a cooling pipeline with cold nitrogen gas flowing through the back of the platen, which takes a long time. When a wafer at room temperature is placed directly onto the cold platen, the platen temperature will experience a brief and significant rise. During ion implantation, ion bombardment itself also causes a rise in wafer temperature, especially when the implantation dose is high and the number of operations is high. These two temperature rises can easily cause the platen temperature to exceed the implantation temperature specification, leading to the need to wait for the platen to cool down again before implantation can begin, or even stopping implantation altogether. Intermittent implantation of the same wafer cassette often occurs. Therefore, whether for rework or product testing, the cooling time required for the equipment is much longer than for other equipment. At the same time, the back-and-forth transport of wafers due to temperature changes can easily lead to increased defects or cause wafer drop due to transport collisions.

[0004] Meanwhile, the current ion implantation equipment operation logic is as follows: after the equipment recognizes the process document (recipe), it first tunes the beam. At this time, the wafer stage does not cool down. After the equipment completes the beam tuning, the wafer stage starts to cool down. When the wafer is transferred to the wafer stage, because the wafer temperature is high, the heat is transferred to the wafer stage, causing it to heat up. The wafer needs to be transferred back to the orienter, and the wafer stage cools down again. This process takes a long time and introduces the risk of defects. Summary of the Invention

[0005] The purpose of this invention is to provide an ion implantation apparatus and ion implantation method to solve at least one of the problems of long wafer stage cooling time and limited production capacity and increased product defects caused by wafer transfer.

[0006] To address the above problems, the present invention provides an ion implantation device, comprising:

[0007] A wafer carrier stage, used to hold a wafer;

[0008] A cooling unit is located on the lower surface of the wafer stage, and the cooling unit cools the wafer stage in real time by introducing coolant.

[0009] A cooling system, connected to the cooling unit, for providing the cooling fluid to the cooling unit;

[0010] A closed-loop automatic controller is connected to the cooling system. The closed-loop automatic controller adjusts the flow rate of the coolant flowing into the cooling unit in the cooling system to maintain the real-time temperature of the wafer stage at the target operating temperature.

[0011] Optionally, the cooling unit is fixedly attached to the lower surface of the slide stage. The cooling unit includes a cooling ring, which is a hollow structure. The cooling ring is also provided with a first inlet and a first outlet. The coolant flows into the hollow structure from the first inlet and flows out from the first outlet.

[0012] Optionally, the cooling system includes a cooler for cooling and circulating the coolant, and the cooler has a second inlet and a second outlet.

[0013] Optionally, the cooling system is provided with a flow control valve, which is located between the first inlet and the second outlet, and is used to regulate the flow rate of the coolant.

[0014] Optionally, the cooling system is provided with a first temperature detector and a second temperature detector.

[0015] Optionally, the first temperature detector is disposed between the first inlet and the second outlet, and the first temperature detector is used to detect the temperature of the coolant flowing into the cooling unit.

[0016] Optionally, the second temperature detector is disposed between the first outlet and the second inlet, and the second temperature detector is used to detect the temperature of the coolant flowing out of the cooling unit.

[0017] Optionally, the closed-loop automatic controller detects and controls the temperature of the first temperature detector to the target operating temperature set in the ion implantation equipment process document. The closed-loop automatic controller controls the opening and closing of the flow control valve. The closed-loop automatic controller synchronously detects the temperature of the second temperature detector, and when the temperature of the second temperature detector is greater than the temperature of the first temperature detector, it automatically increases the opening of the flow control valve to increase the flow rate of the coolant.

[0018] Optionally, the ion implantation equipment is suitable for cryogenic ion implantation processes, wherein the process temperature range of the cryogenic ion implantation process is -120℃ to 0℃.

[0019] An ion implantation method, employing the aforementioned ion implantation equipment, comprising:

[0020] The ion implantation equipment identifies the process document to be executed, and simultaneously performs the beam adjustment of the ion implantation equipment and cools the temperature of the wafer stage to the target operating temperature in real time;

[0021] The wafer is transferred to the wafer stage, and the cooling unit located below the wafer stage compensates for the temperature rise of the wafer stage caused by the heat transfer of the wafer in real time.

[0022] During the ion implantation process, the cooling unit compensates in real time for the temperature rise of the wafer stage caused by the heat generated during the ion implantation process.

[0023] In the ion implantation equipment provided by this invention, a cooling unit is installed below the wafer stage, and a closed-loop automatic controller is used to adjust the coolant flow rate in real time. This ensures that the wafer stage is cooled in real time when the wafer is placed on the stage at room temperature and throughout the ion implantation process, thus maintaining the target operating temperature and effectively avoiding the problem of the wafer stage temperature exceeding specifications due to ion bombardment heating or wafer heat transfer. Therefore, there is no need to repeatedly wait for the wafer stage to cool down before and after each wafer implantation, reducing the need for machine restarts, pauses, or wafer transfer interruptions, significantly improving equipment utilization, and substantially enhancing the capacity and continuity of cryogenic ion implantation.

[0024] Furthermore, because the stage temperature is precisely controlled within the target value, the process of frequently returning the wafer to the alignment unit and repeatedly waiting for cooling due to stage temperature fluctuations is avoided, thus reducing the number of invalid wafer transfers within the machine. This reduces the risk of collisions, wafer drop, or the introduction of defects during transfer, helps maintain the uniformity of wafer surface quality and amorphous layer formation, ultimately reducing lattice defects after annealing, improving device performance consistency, and therefore lowering the wafer defect rate and enhancing product stability. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the cooling system in the ion implantation device provided in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of a cooling unit in an ion implantation device provided in an embodiment of the present invention;

[0027] Figure 3 A flowchart of the operation of an ion implantation device provided in an embodiment of the present invention.

[0028] The labels in the attached figures are explained as follows:

[0029] 1-Slide stage; 2-Cooling unit; 3-First inlet; 4-First outlet; 5-Flow control valve; 6-First temperature detector; 7-Second temperature detector; 8-Second outlet; 9-Second inlet; 10-Cooler. Detailed Implementation

[0030] The following detailed description of an ion implantation device and method provided by the present invention, in conjunction with the accompanying drawings and specific embodiments, provides further clarity. It should be noted that the drawings are all in a very simplified form and use non-precise scales, intended only to facilitate and clarify the illustration of the embodiments of the present invention. Furthermore, the structures shown in the drawings are often part of the actual structure. In particular, different figures may emphasize different aspects and sometimes use different scales. It should be understood that relative terms such as "above," "below," "top," and "bottom" shown in the drawings can be used to describe the relationships between various elements. These relative terms are intended to cover different orientations of elements other than those depicted in the drawings. For example, if the device is inverted relative to the view in the drawings, an element described as "above" another element may now be below that element. It should also be understood that, unless specifically stated or indicated, the terms "first," "second," "third," etc., in the specification are used only to distinguish the various components, elements, steps, etc., in the specification, and are not used to indicate logical or sequential relationships between the various components, elements, steps, etc.

[0031] Figure 1This is a schematic diagram of the cooling system in an ion implantation device provided in an embodiment of the present invention. Figure 1 As shown, this embodiment provides an ion implantation device, including:

[0032] Wafer stage 1, which is used to hold wafers;

[0033] Cooling unit 2, located on the lower surface of the wafer stage 1, cools the wafer stage 1 in real time by introducing coolant;

[0034] A cooling system, connected to the cooling unit 2, for providing the cooling unit 2 with the coolant;

[0035] A closed-loop automatic controller is connected to the cooling system. The closed-loop automatic controller adjusts the flow rate of the coolant flowing into the cooling unit 2 in the cooling system to keep the real-time temperature of the wafer stage 1 at the target operating temperature.

[0036] The ion implantation equipment in this embodiment is suitable for low-temperature ion implantation processes, and the process temperature range of the low-temperature ion implantation process is -120℃ to 0℃.

[0037] Figure 2 This is a schematic diagram of a cooling ring in an ion implantation device provided in an embodiment of the present invention. Figure 2 As shown, the cooling unit 2 includes a cooling ring, which is a hollow structure. The cooling ring is, for example, circular in shape and made of copper. The cooling ring needs to have suitable dimensions, configured to maximize its contact area with the wafer stage 1 while meeting installation and fixing requirements, thereby achieving a faster cooling rate. The outer diameter of the wafer stage 1 is, for example, 320mm~400mm, and the outer diameter of the cooling ring is, for example, 100mm~300mm. The cooling ring is tightly fixed to the lower surface of the wafer stage 1 using thermal grease and bolts, allowing the cooling ring to carry away heat from the wafer stage 1 and thus cool the wafer stage 1 in real time.

[0038] Please continue to refer to this. Figure 1 The cooling unit 2 is provided with a first inlet 3 and a first outlet 4. The first inlet 3 and the first outlet 4 are both located on the same side of the cooling unit 2. The first inlet 3 and the first outlet 4 are both connected to the external pipeline by metal gasket face sealing joints.

[0039] Please continue to refer to this. Figure 1 The cooling system includes a cooler 10, a flow control valve 5, a first temperature detector 6, and a second temperature detector 7.

[0040] The cooler 10 contains a compressor, a heat exchanger, a circulating pump, and a coolant.

[0041] The coolant in this embodiment can be liquid nitrogen, and the operating temperature range of the coolant is, for example, -150℃ to 0℃.

[0042] The cooler 10 is provided with a second outlet 8 and a second inlet 9.

[0043] The cooler 10 is provided with a liquid supply pipeline, which leads out from the second outlet 8, passes through the first temperature detector 6 and the flow control valve 5 in sequence, and finally connects to the first inlet 3 of the cooling unit 2.

[0044] The cooler 10 is also provided with a return pipeline, which is led out from the first outlet 4 of the cooling unit 2, passes through the second temperature detector 7, and returns to the second inlet 9 of the cooler 10.

[0045] This embodiment provides that the ion implantation device is also equipped with a closed-loop automatic controller (not shown in the figure). The closed-loop automatic controller is connected to the cooling system. The closed-loop automatic controller controls the temperature of the wafer stage 1 to be maintained at the target operating temperature by adjusting the flow rate of the coolant flowing into the cooling unit 2 in the cooling system.

[0046] The closed-loop automatic controller is a programmable logic controller (PLC) with a built-in proportional-integral-derivative (PID) control calculation module. The PLC's analog input ports are connected to the signal lines of the first temperature detector 6 and the second temperature detector 7, respectively; the analog output ports are connected to the electric actuator of the flow control valve 5. The PLC also communicates with the main controller of the ion implantation equipment to read the target operating temperature from the current process file, for example, -40℃ to -50℃.

[0047] The control logic of the closed-loop automatic controller is as follows:

[0048] The PLC reads the temperature value T1 of the first temperature detector 6 in real time and adjusts the opening of the flow control valve 5 through a PID algorithm to stabilize T1 at the target operating temperature set in the ion implantation equipment process file.

[0049] The PLC simultaneously reads the temperature value T2 from the second temperature detector 7. When the wafer stage 1 absorbs heat from the wafer or ion beam, causing a temperature rise that results in a temperature difference between T2 and T1 greater than 1.0°C, the PLC automatically increases the opening of the flow control valve 5 by a preset step size, for example, 2%, to increase the coolant flow rate. When the temperature difference between T2 and T1 is less than 0.5°C, the opening is appropriately reduced. Through dynamic adjustment, T2 is kept close to T1, thereby ensuring that the temperature of the wafer stage 1 is within the target operating temperature set in the ion implantation equipment process file.

[0050] like Figure 3 As shown, this embodiment also provides an ion implantation method, including the following steps:

[0051] Step S1: The ion implantation equipment identifies the process document to be executed, and simultaneously performs the beam adjustment of the ion implantation equipment and cools the temperature of the wafer stage 1 to the target operating temperature in real time.

[0052] In step S2, the wafer is transferred to the wafer stage 1, and the cooling unit 2 located below the wafer stage 1 compensates for the temperature rise of the wafer stage 1 caused by the heat transfer of the wafer in real time.

[0053] Step S3: Perform the ion implantation process. The cooling unit 2 compensates in real time for the temperature rise of the wafer stage 1 caused by the heat generated during the ion implantation process.

[0054] The target operating temperature for the ion implantation process is set to -40℃ to -50℃. The process file for the ion implantation equipment is loaded into the main controller of the machine. After the main controller recognizes the process file, it immediately starts the ion source to perform quality analysis, beam adjustment, and beam stability detection. At the same time, the cooler 10 of the cooling system is started to circulate the coolant. The PLC immediately adjusts the flow control valve 5 to an initial opening, such as 20% to 30%. The coolant flows into the cooling unit 2 to cool the wafer stage 1 in real time. The wafer stage 1 begins to cool down from room temperature to the target operating temperature. At the same time, the first temperature detector 6 and the second temperature detector 7 begin to provide real-time temperature feedback, and the PLC enters the PID fine adjustment mode.

[0055] Since the cooling of the wafer stage 1 and the beam adjustment process of the machine are independent and parallel, the wafer stage has stabilized at the target operating temperature when the beam adjustment is completed, without the need for additional waiting time.

[0056] During this process, even without a wafer, the wafer stage 1 continues to maintain the target operating temperature, waiting for the wafer to be transferred.

[0057] The robotic arm delivers the room-temperature wafer into the process chamber. Since the wafer stage 1 is cooled in real time by the cooling unit 2, the temperature rise of the wafer stage 1 caused by wafer heat transfer is compensated in a timely manner.

[0058] The ion beam of the machine begins scanning and implantation. During the implantation process, the ion bombardment generates heat. The PLC automatically adjusts the flow rate according to the real-time fluctuation of T2 to compensate for the temperature rise of the wafer stage caused by the heat generated during the operation. The wafer stage 1 is maintained at the target operating temperature in real time.

[0059] After a wafer is implanted, the robotic arm removes the wafer, and the temperature of the wafer stage 1 is maintained at -40℃ to -50℃. The next wafer can be placed directly on the wafer stage 1 without repeated cooling.

[0060] The ion implantation equipment and method described in this embodiment are compared with traditional cryogenic ion implanters and their operating methods. Both machines perform the same number of wafer operations.

[0061] In this embodiment, the ion implantation equipment beam adjustment, wafer stage 1 cooling to the target operating temperature, and real-time cooling are all performed without repeated cooling, and each wafer is transferred only once.

[0062] Traditional cryogenic ion implanter operations require beam adjustment, cooling, and further cooling due to temperature rise caused by wafer heat transfer and heat generated during operation. Each wafer needs to be transferred 2 to 3 times due to temperature fluctuations.

[0063] Compared to wafers processed by traditional low-temperature ion implantation equipment, the wafers processed by the ion implantation equipment in this embodiment have a 15% to 20% lower defect rate and a 20% to 30% higher production capacity.

[0064] In summary, the ion implantation equipment and method provided by this invention regulate the coolant flow rate through a cooling unit and a closed-loop automatic controller to cool the wafer stage in real time. This ensures that the wafer stage maintains the target operating temperature throughout the wafer placement and ion implantation process, avoiding waiting and interruptions caused by temperature rise. Furthermore, the ion implantation method employs parallel wafer stage cooling and beam adjustment, completing pre-cooling during beam adjustment, shortening the single wafer operation cycle, improving throughput and continuity, and increasing equipment uptime. In addition, precise temperature control avoids frequent wafer transfers and temperature fluctuations, reducing collisions, wafer drop, and particle defects, lowering the product defect rate, and improving product performance stability.

[0065] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. An ion implantation device, characterized in that, include: A wafer carrier stage, used to hold a wafer; A cooling unit is located on the lower surface of the wafer stage, and the cooling unit cools the wafer stage in real time by introducing coolant. A cooling system, connected to the cooling unit, for providing the cooling fluid to the cooling unit; A closed-loop automatic controller is connected to the cooling system. The closed-loop automatic controller adjusts the flow rate of the coolant flowing into the cooling unit in the cooling system to maintain the real-time temperature of the wafer stage at the target operating temperature.

2. The ion implantation apparatus of claim 1, wherein, The cooling unit is fixedly attached to the lower surface of the slide stage. The cooling unit includes a cooling ring, which is a hollow structure. The cooling ring is also provided with a first inlet and a first outlet. The coolant flows into the hollow structure from the first inlet and flows out from the first outlet.

3. The ion implantation apparatus of claim 2, wherein the first and second electrodes are disposed on the same side of the substrate support. 3 The cooling system is provided with a cooler for cooling and circulating the coolant, and the cooler is provided with a second inlet and a second outlet.

4. The ion implantation apparatus of claim 3, wherein the first and second electrodes are disposed on the same side of the substrate support. 5 The cooling system is equipped with a flow control valve, which is located between the first inlet and the second outlet, and is used to regulate the flow rate of the coolant.

5. The ion implantation apparatus of claim 4, wherein the first and second electrodes are disposed on the same side of the substrate support. 5 The cooling system is equipped with a first temperature detector and a second temperature detector.

6. The ion implantation apparatus of claim 5, wherein the first and second electrodes are disposed on the same side of the substrate support. 5 The first temperature detector is disposed between the first inlet and the second outlet, and is used to detect the temperature of the coolant flowing into the cooling unit.

7. The ion implantation apparatus of claim 5, wherein the first and second electrodes are disposed on the same side of the substrate support. 5 The second temperature detector is disposed between the first outlet and the second inlet, and is used to detect the temperature of the coolant flowing out of the cooling unit.

8. The ion implantation apparatus of claim 5, wherein the first and second electrodes are disposed on the same side of the substrate support. 5 The closed-loop automatic controller detects and controls the temperature of the first temperature detector to the target operating temperature set in the ion implantation equipment process document. The closed-loop automatic controller controls the opening and closing of the flow control valve. The closed-loop automatic controller synchronously detects the temperature of the second temperature detector, and when the temperature of the second temperature detector is greater than the temperature of the first temperature detector, it automatically increases the opening of the flow control valve to increase the flow rate of the coolant.

9. The ion implantation apparatus of claim 1, wherein, The ion implantation equipment is suitable for cryogenic ion implantation processes, and the process temperature range of the cryogenic ion implantation process is -120℃ to 0℃.

10. An ion implantation method, characterized by, The ion implantation apparatus described in any one of claims 1 to 9 comprises: The ion implantation equipment identifies the process document to be executed, and simultaneously performs the beam adjustment of the ion implantation equipment and cools the temperature of the wafer stage to the target operating temperature in real time; The wafer is transferred to the wafer stage, and the cooling unit located below the wafer stage compensates for the temperature rise of the wafer stage caused by the heat transfer of the wafer in real time. During the ion implantation process, the cooling unit compensates in real time for the temperature rise of the wafer stage caused by the heat generated during the ion implantation process.

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