An ion beam etching system with endpoint detection function

Abstract

The present invention discloses an ion beam etching system with an endpoint detection function, the ion beam etching system includes a stage and a focusing ring; the stage includes a wafer bearing surface, a factory connection plate and a stage seat, the focusing ring includes a fixing portion, a ring body and a step portion, the ring body is fixed on the stage by the fixing portion, the lower surface of the step portion is connected to the outer diameter of the ring body, and the upper surface of the step portion is higher than the upper surface of the wafer; the endpoint detection device includes a signal collection probe, a signal transmission line and a signal processor; the collection end of the signal collection probe is placed in the hole of the step portion, the data output end of the signal collection probe is connected to the signal transmission line, the signal collection probe collects the real-time spectral signal near the wafer in real time, and sends the collection result to the signal processor via the signal transmission line, and the signal processor calculates the corresponding product group concentration according to the real-time spectral signal. The present invention can improve the intensity, stability and repeatability of the endpoint detection signal, and will not affect the vacuum in the chamber.

Description

Technical Field

[0001] The invention relates to the technical field of ion beam etching systems, and in particular to an ion beam etching system with an endpoint detection function. Background Art

[0002] As the integration density and complexity of devices in integrated circuits continue to increase, strict control of semiconductor process is becoming more and more important. During the process, the deposited layer or growth layer on the surface of the substrate may include various forms of silicon, silicon oxide, silicon nitride, metal, etc., and multiple etching steps will be involved. If the process control is unreasonable, or the machine state (such as gas flow, pressure, temperature) changes slightly, or there are differences between wafer batches, and the etching parameters are not adjusted in time, over-etching will occur, causing damage to the next layer of material or insufficient etching, affecting the next process, and causing device failure. Therefore, in the etching process, in order to selectively and accurately remove the material in the predetermined area, real-time monitoring means are required to control the etching process and etching amount.

[0003] End point detection is a commonly used process control method in etching, and the methods include optical emission spectroscopy (OES), laser interferometry, mass spectrometry, etc. Among them, OES is the most widely used. Its principle is to use the change in the intensity of the wavelength emitted by a certain reactive chemical group or volatile group in the plasma to achieve endpoint detection. At the end point of etching, the light intensity of a specific product group drops sharply; the lower film is about to be exposed to the bombardment of the plasma, and the product groups formed by the reaction between the lower film and the plasma begin to increase. By monitoring certain specific wavelengths in the plasma reaction, the spectral change detected at the expected etching end point is the etching end point.

[0004] OES can detect subtle changes in the film layer very sensitively; it can provide a variety of information in real time during the etching process; it is easy to integrate with the etching machine without affecting the etching process; and its price is only a fraction of that of mass spectrometry detection equipment. However, OES still has shortcomings.

[0005] First, the spectral intensity of OES is proportional to the concentration of product groups. When the etching rate is too slow or the area of ​​the etched film is very small, the obtained OES signal intensity will be very weak, making the endpoint detection invalid. Secondly, OES detects the plasma wavelength of the etching product and is suitable for plasma etching equipment. For ion beam etching equipment, during the etching process, the plasma density on the wafer surface is extremely low; and because the plasma ignition occurs in the ion source chamber, it is easily interfered by the ion source signal, so it is difficult to accurately monitor the real-time status of the film layer on the wafer surface. Finally, because the change in light intensity is usually observed from the observation window on the reaction chamber, as the etching product is deposited on the observation window, the OES signal will gradually decrease, affecting the detection. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides an ion beam etching system with an endpoint detection function, which can improve the endpoint detection signal intensity, improve the stability and repeatability of the endpoint detection, and will not affect the chamber vacuum.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The embodiment of the present invention provides an ion beam etching system with an endpoint detection function, the ion beam etching system includes a stage and a focusing ring 20; the stage includes a wafer carrying surface 10 exposed to the vacuum of the reaction chamber, a factory service connection plate 30 isolating the vacuum of the reaction chamber from the atmosphere, and a stage seat 40 communicated with the atmosphere, and the focusing ring 20 is arranged around the wafer carrying surface 10; the focusing ring 20 includes a fixing part, a ring body and a step part, the ring body is fixed to the stage through the fixing part, the wafer 90 is placed on the ring body, the lower surface of the step part is connected to the outer diameter of the ring body, and the upper surface of the step part is higher than the upper surface of the wafer 90; the endpoint detection device includes a signal collection probe 100, a signal transmission line 102 and a signal processor;

[0009] A hole 50 is provided in the step portion; the collecting end of the signal collecting probe 100 is placed in the hole 50, and the data output end of the signal collecting probe 100 is connected to the signal transmission line 102; the signal collecting probe 100 collects the real-time spectral signal near the wafer 90 in real time, and then sends the collected result to the signal processor via the signal transmission line 102, so that the signal processor calculates the corresponding product group concentration according to the real-time spectral signal.

[0010] Furthermore, the hole 50 is a blind hole, and the focusing ring 20 is made of a transparent material; the signal acquisition probe is installed near the closed end of the blind hole to collect the real-time spectral signal passing through the closed end of the blind hole.

[0011] Furthermore, the focusing ring 20 is made of sapphire glass, transparent ceramic or quartz glass.

[0012] Further, the hole 50 is a through hole 50;

[0013] The data output end of the signal collection probe 100 extends out from the focusing ring 20 and is sealed and connected to the signal transmission line 102 via a sealed adapter unit installed on the factory connection plate 30 .

[0014] Further, the sealed adapter unit includes a signal transmission line connector 101 and an interface mechanism arranged on the factory service connection plate 30;

[0015] The signal transmission line 102 is connected to one end of the signal transmission line connector 101 , and the data output end of the signal acquisition probe is sealed and connected to the other end of the signal transmission line connector 101 through an interface mechanism.

[0016] Further, the interface mechanism includes a sealing ring 60, a signal adapter plate 70 and an adapter pressure plate 80;

[0017] A groove is provided at the place where the factory service connection plate 30 and the tail end of the hole 50 are connected, and the sealing ring 60 is placed in the groove; the data output end of the signal collection probe 100 passes through the sealing ring 60 and is connected to the signal transmission line connector 101 through the signal adapter plate 70; the adapter pressure plate 80 is fixed on the factory service connection plate 30 through fixing parts, and the adapter pressure plate 80 is tightly filled between the signal adapter plate 70 and the signal transmission line connector 101, applying an extrusion force to the signal adapter plate 70 and the sealing ring 60, so that the sealing ring 60 is squeezed and deformed to form a sealed connection between the data output end and the signal transmission line connector 101.

[0018] Furthermore, the signal transfer board 70 is made of a transparent material, and its outer side is covered with an opaque cladding structure.

[0019] Furthermore, a threaded hole is provided on the adapter pressure plate 80 , and a threaded structure matching the outer wall of the signal transmission line connector 101 is provided on the inner wall of the threaded hole. The signal transmission line connector 101 is fixed to the adapter pressure plate 80 by being screwed into the threaded hole.

[0020] Furthermore, a straight hole is provided on the adapter pressure plate 80, and the signal adapter connector is fixed in the straight hole through a fixing member.

[0021] Furthermore, the carrier has a rotation device; the signal transmission line 102 is buried in the carrier seat 40, and its end away from the signal collection probe 100 passes through the hollow cavity inside the rotating shaft of the rotation device and out of the vacuum chamber, and is connected to a signal processor arranged outside the vacuum chamber.

[0022] The beneficial effects of the present invention are:

[0023] The ion beam etching system with endpoint detection function proposed by the present invention places a signal collection probe in a focusing ring so that endpoint detection can be performed at a position close to the wafer, thereby improving the endpoint detection signal strength; at the same time, the focusing ring is always bombarded by the ion beam during the etching process, thereby avoiding the deposition of etching products that causes the signal strength to decrease, thereby improving the stability and repeatability of the endpoint detection; in addition, the connection line of the detection probe can be connected to the outside of the chamber through the internal structure of the carrier, and will not affect the chamber vacuum. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1is a side view of a focus ring according to an embodiment of the present invention.

[0025] Figure 2 4 is a top view of a focus ring according to an embodiment of the present invention.

[0026] Figure 3 It is a schematic structural diagram of an ion beam etching system with an endpoint detection function according to an embodiment of the present invention.

[0027] Figure 4 It is a schematic structural diagram of a sealing adapter unit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention will now be described in further detail with reference to the accompanying drawings.

[0029] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0030] The endpoint detection device of this embodiment is designed based on the structure of a conventional ion beam etching system, does not affect the normal use of the ion beam etching system, and does not require a significant change in the structure of the ion beam etching system. Therefore, the endpoint detection device of this embodiment has a very high value for popularization and application.

[0031] (I) End point detection principle

[0032] See also Figures 1 to 3 The ion beam etching system includes a carrier and a focusing ring 20; the carrier is used to carry a wafer 90 and is located in an IBE etching reaction chamber. The carrier includes a wafer carrying surface 10 exposed to the vacuum of the reaction chamber, a factory connection plate 30 isolating the vacuum in the reaction chamber from the atmosphere, and a carrier seat 40 communicated with the atmosphere. The focusing ring 20 is arranged around the wafer carrying surface 10; the focusing ring 20 includes a fixing portion, a ring body and a step portion. The ring body is fixed to the carrier through the fixing portion. The wafer 90 is placed on the ring body. The lower surface of the step portion is connected to the outer diameter of the ring body, and the upper surface of the step portion is higher than the upper surface of the wafer 90.

[0033] The endpoint detection device is arranged on the stage, and includes a signal collection probe 100, a signal transmission line 102 and a signal processor. A hole 50 is arranged in the step portion; the collection end of the signal collection probe 100 is placed in the hole 50, and the data output end of the signal collection probe 100 is connected to the signal transmission line 102; the signal collection probe 100 collects the real-time spectrum signal near the wafer 90 in real time, and then sends the collection result to the signal processor via the signal transmission line 102, so that the signal processor calculates the corresponding product group concentration according to the real-time spectrum signal.

[0034] This embodiment places the signal collection probe in the focusing ring so that it can perform endpoint detection at a position close to the wafer, thereby improving the endpoint detection signal strength; at the same time, the focusing ring is constantly bombarded by the ion beam during the etching process, avoiding the deposition of etching products that lead to a decrease in signal strength, thereby improving the stability and repeatability of endpoint detection.

[0035] The carrier has a self-rotating device. During the process, the wafer carrying surface 10 of the carrier is in a self-rotating state. The carrier is rotated around the rotating shaft through a rotating shaft connected to the cavity, so that the wafer carrying surface 10 faces the ion beam at a certain angle (-90° to 90°). The ion beam physically or chemically etches the film layer on the surface of the wafer 90 at a certain angle. The signal collection probe 100 collects the spectral signal on the surface of the wafer 90 during the etching process, and transmits the collected spectral signal to the signal processor via the signal transmission line 102, so that the signal processor processes the spectral signal.

[0036] (II) Sealing structure

[0037] (2.1) Hole 50 is a blind hole

[0038] The hole 50 is preferably a blind hole, and the end of the hole 50 close to the signal acquisition probe 100 for receiving the light intensity signal is the closed end of the blind hole. At this time, the focusing ring 20 should be made of a transparent material, preferably sapphire glass, transparent ceramics, quartz glass, etc., to facilitate the signal acquisition probe 100 to receive the spectral signal through the closed end of the blind hole.

[0039] (2.2) Hole 50 is a through hole

[0040] As a preferred example, in order to reduce the difficulty of processing the hole 50, the hole 50 can be set as a through hole (in this case, the focus ring material can be a transparent material or an opaque material, such as ceramic, etc.), and a sealing structure should be provided at the junction of the signal acquisition probe 100 and the signal transmission line. Specifically, the data output end of the signal collection probe 100 extends from the focus ring 20 and is sealed and connected to the signal transmission line 102 through a sealed adapter unit installed on the factory service connection plate 30.

[0041] Exemplarily, the hole 50 is an arc-shaped structure, one end of which leads to the factory connection plate 30 and is perpendicular to the factory connection plate 30, and the other end extends to the inner wall of the step portion, is located above the wafer 90 and forms an angle with the wafer plane to avoid structural interference between the information collection probe 100 and the wafer 90.

[0042] (2.3) Sealed adapter unit

[0043] The sealed adapter unit includes a signal transmission line connector 101 and an interface mechanism arranged on the factory service connection plate 30; the signal transmission line 102 is connected to one end of the signal transmission line connector 101, and the data output end of the signal acquisition probe is sealed and connected to the other end of the signal transmission line connector 101 through the interface mechanism.

[0044] See also Figure 3 and Figure 4 , one end of the signal collection probe 100 connected to the signal transmission line connector 101 extends out of the focusing ring 20, and is connected to the signal transmission line connector 101 through the interface mechanism on the factory service connection board 30. The interface mechanism on the factory service connection board 30 includes a sealing ring 60, a signal adapter board 70 (the signal adapter board 70 is made of a transparent material, preferably sapphire or glass; to prevent the optical signal from leaking out, the signal adapter board 70 is covered with a cortex) and an adapter pressure plate 80. A groove is provided at the place where the factory service connection board 30 connects to the tail end of the hole 50, and the sealing ring 60 is placed in the groove. One end of the signal collection probe 100 connected to the signal transmission line connector 101 passes through the sealing ring 60. The signal collection probe 100 is connected to the signal transmission line connector 101 through the signal adapter board 70. One end of the signal adapter board 70 is tightly combined with the signal collection probe 100, and the other end of the signal adapter board 70 is tightly combined with the signal transmission line connector 101. The adapter plate 80 is pressed on the side of the signal adapter plate 70 that is connected to the signal transmission line connector 101, and forms an extrusion force on the signal adapter plate 70 and the sealing ring 60, and completes the sealing between the atmosphere and the vacuum through the extrusion and deformation of the sealing ring 60. The adapter plate 80 is fixed on the factory service connection plate 30 through fixing parts.

[0045] On one hand, the adapter plate 80 can press the signal adapter plate 70, and at the same time, a fixing hole is provided on the adapter plate 80. The fixing hole is opened at the junction of the adapter plate 80 and the signal transmission line connector 101. The fixing hole can be a threaded hole or a straight hole. When the fixing hole is a threaded hole, the outer periphery of the signal transmission line connector 101 is provided with a thread matching the fixing hole, and the signal transmission line connector 101 is screwed into the fixing hole for fixing; when the fixing hole is a straight hole, the signal transmission line connector 101 extends into the fixing hole and is fixed by a fixing piece. The signal transmission line connector 101 is coaxial with the signal collection probe 100.

[0046] (2.4) Signal transmission line structure

[0047] The signal transmission line connector 101 is connected to the signal transmission line 102. The signal transmission line 102 is placed in the stage seat 40. The end of the signal transmission line 102 that is away from the signal transmission line connector 101 passes through the hollow structure inside the rotating shaft and passes out of the cavity. Finally, the signal transmission line 102 is connected to the signal processor for light intensity processing. Therefore, the connection line of the detection probe is connected to the outside of the chamber through the internal structure of the stage, and will not affect the vacuum of the chamber.

[0048] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. An ion beam etching system with endpoint detection function, characterized in that: The ion beam etching system comprises a carrier and a focusing ring (20); The carrier comprises a wafer carrying surface (10) exposed to the vacuum of the reaction chamber, a factory connection plate (30) isolating the vacuum in the reaction chamber from the atmosphere, and a carrier seat (40) communicated with the atmosphere, and a focusing ring (20) is arranged around the wafer carrying surface (10); The focusing ring (20) comprises a fixing portion, a ring body and a step portion, the ring body is fixed on the carrier through the fixing portion, the wafer (90) is placed on the ring body, the lower surface of the step portion is connected to the outer diameter of the ring body, and the upper surface of the step portion is higher than the upper surface of the wafer (90); The endpoint detection device comprises a signal collection probe (100), a signal transmission line (102) and a signal processor; A hole (50) is provided in the step portion, a collection end of the signal collection probe (100) is placed in the hole (50), a data output end of the signal collection probe (100) is connected to a signal transmission line (102), the signal collection probe (100) collects real-time spectral signals near the wafer (90) in real time, and sends the collection results to a signal processor via the signal transmission line (102), and the signal processor calculates the corresponding product group concentration according to the real-time spectral signals; The hole (50) is a through hole (50); the hole (50) is an arc-shaped structure, one end of which leads to the factory connection plate (30) and is perpendicular to the factory connection plate (30), and the other end extends to the inner wall of the step portion, is located above the wafer (90) and forms an angle with the wafer plane; the data output end of the signal collection probe (100) extends from the focusing ring (20) and is sealed and connected to the signal transmission line (102) through a sealed adapter unit installed on the factory connection plate (30).

2. The ion beam etching system with endpoint detection function according to claim 1, characterized in that: The hole (50) is a blind hole, and the focusing ring (20) is made of a transparent material; The signal collection probe (100) is installed near the closed end of the blind hole to collect the real-time spectrum signal passing through the closed end of the blind hole.

3. The ion beam etching system with endpoint detection function according to claim 2, characterized in that: The focusing ring (20) is made of sapphire glass, transparent ceramic or quartz glass.

4. The ion beam etching system with endpoint detection function according to claim 1, characterized in that: The sealed adapter unit comprises a signal transmission line connector (101) and an interface mechanism arranged on a factory service connection plate (30); The signal transmission line (102) is connected to one end of the signal transmission line connector (101), and the data output end of the signal collection probe (100) is sealedly connected to the other end of the signal transmission line connector (101) via an interface mechanism.

5. The ion beam etching system with endpoint detection function according to claim 4, characterized in that: The interface mechanism comprises a sealing ring (60), a signal adapter plate (70) and an adapter pressure plate (80); A groove is provided at the place where the factory service connection plate (30) and the rear end of the hole (50) meet, and a sealing ring (60) is placed in the groove; The data output end of the signal collection probe (100) passes through the sealing ring (60) and is connected to the signal transmission line connector (101) via the signal adapter plate (70); The adapter pressure plate (80) is fixed on the factory service connection plate (30) by means of fixing parts, and the adapter pressure plate (80) is tightly filled between the signal adapter plate (70) and the signal transmission line connector (101), exerting an extrusion force on the signal adapter plate (70) and the sealing ring (60), so that the sealing ring (60) is squeezed and deformed to form a sealed connection between the data output end and the signal transmission line connector (101).

6. The ion beam etching system with endpoint detection function according to claim 5, characterized in that: The signal transfer plate (70) is made of a transparent material, and its outer side is covered with a light-proof cladding structure.

7. The ion beam etching system with endpoint detection function according to claim 5, characterized in that: The adapter pressure plate (80) is provided with a threaded hole, the internal thread of the threaded hole is adapted to the outer wall of the signal transmission line connector (101), and the signal transmission line connector (101) is fixed to the adapter pressure plate (80) by screwing into the threaded hole.

8. The ion beam etching system with endpoint detection function according to claim 5, characterized in that: The adapter pressing plate (80) is provided with a straight hole, and the signal adapter connector is fixed in the straight hole via a fixing piece.

9. The ion beam etching system with endpoint detection function according to any one of claims 1 to 8, characterized in that: The platform has a rotation device; The signal transmission line (102) is buried in the carrier seat (40), and one end thereof away from the signal collection probe (100) passes through the hollow cavity inside the rotating shaft of the rotation device and out of the vacuum chamber to be connected to a signal processor arranged outside the vacuum chamber.

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