A bottom air curtain protection device for deep ultraviolet wafer defect detection

Abstract

The present invention discloses a bottom air curtain protection device for deep ultraviolet wafer defect detection, which relates to the field of semiconductor technology and solves the problems of complex structure of the air curtain protection device, non-homogenized gas, and easy turbulence and backflow of gas. The present invention includes a connector and an air curtain member, the upper end of the connector is connected to the wafer defect detection system, and the lower end is connected to the air curtain member, thereby forming a cavity; the cavity is arranged below the objective lens of the wafer defect detection system; a through hole is arranged in the center of the air curtain member, and a T-shaped groove is arranged on the surface facing the cavity, and the T-shaped groove is connected to the through hole; gas is introduced into the cavity to form an air curtain below the objective lens of the wafer defect detection system, and the gas mainly flows out along the direction of the trumpet-shaped groove. The present invention is directly connected to the gas path of the wafer defect detection system, and the airflow in the cavity of the protective device is homogenized by the T-shaped groove to avoid the occurrence of backflow and turbulence, and the defect detection of the wafer is not affected while protecting the objective lens.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a bottom air curtain protection device for deep ultraviolet wafer defect detection. Background Art

[0002] Semiconductor products are widely used in various fields, such as communications, computers, consumer electronics, etc. These products have extremely high reliability requirements, and any tiny defects may cause product failure or performance degradation. Wafer surface defect detection is an important means to ensure product reliability. With the continuous improvement of semiconductor chip manufacturing technology, the feature size of chips is getting smaller, the size of wafers is getting larger, and the width of wafer cutting lanes is getting narrower. These factors have greatly increased the difficulty of wafer surface defect detection in the dicing process. Deep UV bright field wafer defect detection technology came into being.

[0003] Deep ultraviolet wafer surface defect detection is an advanced semiconductor detection technology that uses the high energy and high resolution characteristics of deep ultraviolet light to perform fine defect detection on the wafer surface. It has the characteristics of high resolution, high sensitivity, non-basic detection, and rapid detection.

[0004] During the use of the deep ultraviolet wafer surface defect detection microscopic imaging system, the chemical reagents remaining on the wafer surface will gradually evaporate and contaminate the objective lens; particulate pollutants in the environment will also adhere to the lens surface during use. Eventually, as the use time increases, the imaging quality of the imaging system will be affected. Due to the extremely high requirements for the objective lens in the deep ultraviolet spectrum, after the imaging system lens is contaminated, the specific contamination situation needs to be determined, and replacement is difficult and costly, which affects the production speed and causes significant losses.

[0005] The existing technology includes three technical directions, as follows:

[0006] 1) Install a lens holder at the bottom of the objective lens and install a protective film on the lens holder. This technology uses a very thin protective film that is easy to break and has a short lifespan. It needs to be replaced frequently and is extremely difficult to install. It requires special personnel to replace it and has a very high cost.

[0007] 2) The Chinese patent with publication number CN110554570A discloses "A pollution control device and method, objective lens system and photolithography equipment". The gas outlet direction of this patent is uncontrollable. During use, when the wafer moves, it is easy to cause uneven gas distribution;

[0008] 3) The Chinese patent with publication number CN112748641A discloses an "air curtain protection device at the bottom of the lens". The design and processing of this patent are complex, and small holes need to be processed. The processing cycle is long, the internal cleaning is difficult, and pollutants are easily left. In addition, an independent exhaust circuit is required, which takes up equipment space.

[0009] The existing technology occupies a large space and has high requirements for optical indicators, especially the working distance. At the same time, the gas inlet is closely connected to the anti-pollution device, and the gas is not well homogenized, which is prone to turbulence, backflow and other problems. Summary of the invention

[0010] In order to solve the above-mentioned problems of the existing air curtain protection device, such as complex structure, non-homogenized gas, easy turbulence and backflow of gas, the present invention proposes a bottom air curtain protection device for deep ultraviolet wafer defect detection. The present invention is directly connected to the gas path of the wafer defect detection system, and the airflow in the cavity of the protection device is homogenized through the T-slot to avoid the occurrence of backflow and turbulence, while protecting the objective lens, it does not affect the defect detection of the wafer.

[0011] The present invention proposes a bottom air curtain protection device for deep ultraviolet wafer defect detection, which specifically comprises a connecting piece and an air curtain piece, wherein the upper end of the connecting piece is connected to a wafer defect detection system, and the lower end is connected to the air curtain piece, thereby forming a cavity; the cavity is arranged below an objective lens of the wafer defect detection system; a through hole is arranged at the center of the air curtain piece, a T-shaped groove is arranged on the surface facing the cavity, and the T-shaped groove is connected to the through hole; a wafer to be detected is arranged below the air curtain piece; gas is introduced into the cavity to form an air curtain below the objective lens of the wafer defect detection system.

[0012] Furthermore, the chamber is connected to a gas supply system of a wafer defect detection system.

[0013] Furthermore, the T-shaped slot includes a transverse slot and a vertical slot, one end of the vertical slot is connected to the middle position of the transverse slot, and the other end is connected to the through hole.

[0014] Furthermore, the width of the vertical groove is the same as the width of the through hole.

[0015] Furthermore, a trumpet-shaped groove is arranged on the outward surface of the air curtain member, and the trumpet-shaped groove is connected to the through hole.

[0016] Furthermore, the air inlet end of the trumpet-shaped groove is connected to the through hole, and the air outlet end coincides with the edge of the air curtain member.

[0017] Furthermore, the width of the air inlet end of the trumpet-shaped groove is the same as the width of the through hole.

[0018] Furthermore, the trumpet-shaped groove and the T-shaped groove are respectively arranged on two opposite sides of the through hole.

[0019] Furthermore, the through hole is in a rectangular shape.

[0020] Furthermore, the overall thickness of the connecting member and the air curtain member is less than 15.0 mm, and the thickness of the air curtain member is less than 2.0 mm.

[0021] The beneficial effects of the bottom air curtain protection device for deep ultraviolet wafer defect detection described in the present invention are:

[0022] (1) The bottom air curtain protection device for deep ultraviolet wafer defect detection described in the present invention overcomes the problems of complex structure, non-homogenized gas, and easy turbulence and backflow of gas in existing air curtain protection devices. The nitrogen gas entering the cavity is homogenized and guided through the T-shaped grooves arranged on the upper surface of the air curtain member, so that the nitrogen gas can smoothly flow out from the through hole in the center of the air curtain member after filling the cavity, thereby avoiding the backflow of nitrogen gas at the through hole and the turbulence affecting the detection effect of the defect detection device on the wafer. The overall structure is simple, the processing is convenient, and it is easy to clean and install, and has strong anti-pollution ability;

[0023] (2) The bottom air curtain protection device for deep ultraviolet wafer defect detection described in the present invention can quickly and directionally guide nitrogen from between the air curtain and the wafer through the trumpet-shaped grooves provided on the lower surface of the air curtain, so that the nitrogen can flow better along the lower surface of the air curtain, and the outlet direction can be controlled. The direction of gas discharge can be independently selected in the equipment, and while ensuring pollution-free, inert atmosphere working conditions, the safety of other components in the whole machine can also be guaranteed;

[0024] (3) The bottom air curtain protection device for deep ultraviolet wafer defect detection described in the present invention directly integrates the air curtain protection device and the wafer defect detection microscopic imaging system together. The two share an air path, which reduces equipment redundancy and does not require an additional sealing device for the imaging system. While saving structural design, the last lens can also be hollowed out accordingly, which is convenient for integration, installation and adjustment of the microscopic imaging system, greatly increasing the stability of the imaging system. The air curtain protection device and the imaging system are installed vertically, and no radial force is transmitted to the lens in the imaging system, thereby ensuring the surface accuracy to the greatest extent.

[0025] (4) The bottom air curtain protection device for deep ultraviolet wafer defect detection described in the present invention can effectively protect the objective lens of the wafer defect detection microscopic imaging system. The through-hole area is much smaller than the area of ​​the wafer to be detected. The small through-hole area increases the piezoresistance of the wafer defect detection microscopic imaging system, which can ensure that the imaging system can be more easily filled with nitrogen and the nitrogen is evenly distributed. While preventing the objective lens from being accidentally hit, it can also more effectively prevent the objective lens from being contaminated, and no additional exhaust circuit structure is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] In the attached picture:

[0028] Figure 1 It is a schematic diagram of the three-dimensional structure of a bottom air curtain protection device for deep ultraviolet wafer defect detection according to the present invention;

[0029] Figure 2 It is a top view of a bottom air curtain protection device for deep ultraviolet wafer defect detection according to the present invention;

[0030] Figure 3 It is a bottom view of a bottom air curtain protection device for deep ultraviolet wafer defect detection according to the present invention;

[0031] Figure 4 It is a three-dimensional structural schematic diagram of a connecting piece of a bottom air curtain protection device for deep ultraviolet wafer defect detection according to the present invention;

[0032] Figure 5 It is a top view of a connector of a bottom air curtain protection device for deep ultraviolet wafer defect detection according to the present invention;

[0033] Figure 6 It is a bottom view of a connector of a bottom air curtain protection device for deep ultraviolet wafer defect detection according to the present invention;

[0034] Figure 7 It is a three-dimensional structural schematic diagram of an air curtain component of a bottom air curtain protection device for deep ultraviolet wafer defect detection according to the present invention;

[0035] Figure 8 It is a top view of an air curtain member of a bottom air curtain protection device for deep ultraviolet wafer defect detection according to the present invention;

[0036] Fig. 9 It is a bottom view of an air curtain member of a bottom air curtain protection device for deep ultraviolet wafer defect detection according to the present invention;

[0037] Fig.10 It is a cross-sectional velocity vector diagram in the vertical direction of a bottom air curtain protection device for deep ultraviolet wafer defect detection according to the present invention;

[0038] Fig.11 It is a velocity cloud diagram of the surface of the wafer to be inspected below the bottom air curtain protection device of the deep ultraviolet wafer defect inspection according to the present invention;

[0039] Fig.12 It is a cloud diagram of oxygen mass fraction between lenses inside a wafer defect detection microscopic imaging system connected to a bottom air curtain protection device for deep ultraviolet wafer defect detection described in the present invention.

[0040] Among them: 1-connecting piece, 2-air curtain piece, 3-through hole, 4-T-slot, 5-trumpet-shaped slot, 6-horizontal slot, 7-vertical slot. DETAILED DESCRIPTION

[0041] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0043] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0044] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] Specific implementation method 1: See Figure 1-Figure 12The present embodiment is described in detail. The bottom air curtain protection device for deep ultraviolet wafer defect detection described in the present embodiment specifically includes a connector 1 and an air curtain 2. The connector 1 is an annular structure, and the air curtain 2 is a circular structure. The upper end of the connector 1 is connected to the wafer defect detection microscopic imaging system by bolts, and the lower end is connected to the air curtain 2 by bolts. A cavity is formed below the objective lens of the wafer defect detection microscopic imaging system. The cavity is directly connected to the nitrogen gas supply system of the wafer defect detection microscopic imaging system. The overall thickness of the air curtain protection device is less than 15.0 mm. The air curtain 2 is The thickness is less than 2.0mm; a through hole 3 is arranged at the center of the air curtain member 2, and the through hole 3 is rectangular in shape. The area of ​​the through hole 3 is much smaller than the area of ​​the wafer to be inspected, and the deep ultraviolet light emitted by the wafer defect detection microscopic imaging system passes through the through hole 3 to detect the wafer surface; the wafer to be inspected is arranged under the air curtain member 2; nitrogen is introduced into the cavity through the nitrogen supply system of the wafer defect detection microscopic imaging system, and a nitrogen air curtain is formed under the objective lens of the wafer defect detection microscopic imaging system to protect the objective lens and prevent pollution.

[0046] The air curtain member 2 is provided with a T-shaped slot 4 on one side of the surface facing the cavity, and the T-shaped slot 4 is connected to the through hole 3. The T-shaped slot 4 includes a horizontal slot 6 and a vertical slot 7, one end of the vertical slot 7 is connected to the middle position of the horizontal slot 6, and the other end is connected to a straight edge of the through hole 3, and the width of the vertical slot 7 is the same as the width of the through hole 3. Figure 8 As shown. When the equipment is running, nitrogen is introduced into the wafer defect detection microscopic imaging system, and the nitrogen flows from top to bottom, is homogenized in the cavity between the connector 1 and the air curtain 2, and is guided to the central through hole 3 through the T-slot 4 on the upper surface of the air curtain 2. The gas itself has a certain speed, and under the support of gravity, it flows downward at the central through hole 3, so that the through hole 3 is filled with nitrogen with a certain positive pressure, which plays a role in preventing pollution.

[0047] The outward surface of the air curtain member 2 is provided with a trumpet-shaped groove 5, which is connected to the through hole 3. The air inlet end of the trumpet-shaped groove 5 is connected to a straight edge of the through hole 3, and the air outlet end is arc-shaped and coincides with the edge of the air curtain member 2. The distance between the wafer to be inspected and the air curtain member 2 is very small, and the pressure resistance of nitrogen flowing directly downward is very large. The trumpet-shaped groove 5 is used to guide the nitrogen, so that the nitrogen can flow better along the lower surface of the air curtain member 2, and the gas outlet direction can be controlled.

[0048] like Figure 7As shown, the trumpet-shaped groove 5 on the lower surface of the air curtain member 2 and the T-shaped groove 4 on the upper surface of the air curtain member 2 are respectively arranged on the left and right sides opposite to the through hole, and the axis of the trumpet-shaped groove 5 coincides with the axis of the T-shaped groove 4. After the nitrogen is homogenized in the cavity, under the drainage effect of the T-shaped groove 4, the nitrogen flows into the through hole 3 along the direction of the vertical groove 7 of the T-shaped groove 4. After passing through the through hole 3, the nitrogen directly enters the air inlet side of the trumpet-shaped groove 5 and is directly discharged along the trumpet-shaped groove 5, so that no backflow phenomenon and no turbulence will occur during the entire flow process of the nitrogen.

[0049] A method for using an air curtain protective device at the bottom of a deep ultraviolet wafer defect detection lens comprises the following steps:

[0050] Step 1: Determine the overall thickness, the size of the connector 1 and the size of the air curtain 2 by analyzing the optical indicators, and process the connector 1 and the air curtain 2;

[0051] Step 2: Deeply clean the processed connecting piece 1 and the air curtain piece 2;

[0052] Step 3, assembling the connecting piece 1 and the air curtain piece 2 into an air curtain protective device;

[0053] Step 4: Connect the air curtain protection device to the wafer defect detection microscopic imaging system;

[0054] Step 5: According to the imaging effect, adjust the nitrogen pressure and flow rate of the wafer defect detection microscopic imaging system;

[0055] Step 6: Select the best imaging effect and determine the values ​​of nitrogen pressure and flow rate;

[0056] Step 7: Equip the wafer defect detection microscopic imaging system into the whole machine for use.

[0057] Figure 10-12 The figure shows the simulation of gas flow between the wafer defect detection microscopic imaging system, the air curtain protection device and the wafer. During the simulation, the air curtain protection device was connected to a deep ultraviolet wafer defect detection microscopic imaging system. The overall thickness of the air curtain protection device was 13.2 mm, the thickness of the air curtain component 2 was 1.2 mm, the bottom surface of the air curtain component 2 was 0.4 mm away from the wafer surface, and the nitrogen pressure at the air inlet of the wafer defect detection microscopic imaging system was 5.0 psi, with a flow rate of 1.25 L / min. The simulation shows that in the wafer defect detection microscopic imaging system, the distance between the two closest lenses is 0.02 mm. After stabilization, the nitrogen concentration in the lens gap is greater than 99.999%. The air curtain protection device can stably discharge nitrogen, and there is no backflow or turbulence at the 3 through holes in the center, as shown in the figure. Fig.11The gas is mainly discharged in a predetermined direction along the trumpet-shaped groove 5; the airflow velocity on the wafer surface is less than 0.01 m / s, approaching 0. While ensuring that the wafer defect detection microscopic imaging system is filled with nitrogen without dead zones and the airflow in the central optical path is stable, the wafer surface is also protected.

[0058] During the physical experiment, the overall thickness of the air curtain protection device is 14.0 mm, the thickness of the air curtain 2 is 1.4 mm, the nitrogen pressure at the air inlet of the wafer defect detection microscopic imaging system is 4-7 psi, the nitrogen flow rate is 0.8-5.5 L / min, and the ventilation volume required by the whole machine is 649.3 cm 3 After the whole machine is inflated for 10 minutes, the nitrogen concentration at the outlet of through hole 3 is greater than 99.0%. After continuous inflation for 6 hours, the nitrogen concentration at the outlet of through hole 3 is greater than 99.999%. After the whole machine is ventilated stably and the nitrogen concentration reaches the standard, it can work in the deep ultraviolet spectrum and can form clear images. Under long-term operation, the lenses of the microscopic imaging system are not contaminated and the optical indicators are normal.

[0059] The deep ultraviolet wafer defect detection bottom air curtain protection device described in the present invention can also be correspondingly applied to the I-line wafer defect detection microscopic imaging system, and can also be used in some lithography machines.

[0060] Summarizing the above implementation cases, the bottom air curtain protection device for deep ultraviolet wafer defect detection described in the present invention overcomes the problems of complex structure, unhomogenized gas, and easy turbulence and backflow of gas in existing air curtain protection devices. The nitrogen entering the cavity is homogenized and guided by the T-shaped groove 4 arranged on the upper surface of the air curtain member 2, so that the nitrogen can smoothly flow out from the through hole 3 in the center of the air curtain member 2 after filling the cavity, thereby avoiding the backflow of nitrogen at the through hole 3 and the turbulence affecting the detection effect of the defect detection device on the wafer. The overall structure is simple, the processing is convenient, and it is easy to clean and install, and has strong anti-pollution ability; the bottom air curtain protection device for deep ultraviolet wafer defect detection described in the present invention can quickly and directionally guide nitrogen from between the air curtain member 2 and the wafer through the trumpet-shaped groove 5 arranged on the lower surface of the air curtain member 2, so that the nitrogen can flow better along the lower surface of the air curtain member 2, and the outlet direction is controllable; the bottom air curtain protection device for deep ultraviolet wafer defect detection described in the present invention can be connected to the air curtain protection device and the wafer by connecting the air curtain protection device and the wafer. The defect detection microscopic imaging system is directly integrated together, and the two share an air circuit, which reduces equipment redundancy, and the imaging system does not need an additional sealing device. While saving structural design, the last lens can also be hollowed out accordingly, which is convenient for the integration, installation and adjustment of the microscopic imaging system, and greatly increases the stability of the imaging system; the air curtain protection device is light and easy to install, and is installed vertically with the imaging system. It does not transmit radial force to the lens in the imaging system, and guarantees the surface accuracy to the greatest extent; the deep ultraviolet wafer defect detection bottom air curtain protection device described in the present invention can effectively protect the objective lens of the wafer defect detection microscopic imaging system, the area of ​​the through hole 3 is much smaller than the area of ​​the wafer to be detected, and the small through hole area increases the piezoresistance of the wafer defect detection microscopic imaging system, which can ensure that the imaging system can be more easily filled with nitrogen, and the nitrogen is evenly distributed. While preventing the objective lens from being accidentally hit, it can also more effectively prevent the objective lens from being contaminated, and no additional exhaust circuit structure is required.

[0061] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the invention. It can also be a reasonable combination of the features recorded in the above implementation methods. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A bottom air curtain protection device for deep ultraviolet wafer defect detection, characterized in that: The invention comprises a connecting member (1) and an air curtain member (2), wherein the upper end of the connecting member (1) is connected to a wafer defect detection system, and the lower end is connected to the air curtain member (2), thereby forming a cavity; the cavity is arranged below an objective lens of the wafer defect detection system; a through hole (3) is arranged at the center of the air curtain member (2), and a T-shaped groove (4) is arranged on the surface facing the cavity, and the T-shaped groove (4) is connected to the through hole (3); a wafer to be detected is arranged below the air curtain member (2); gas is introduced into the cavity to form an air curtain below the objective lens of the wafer defect detection system; The outwardly facing surface of the air curtain member (2) is provided with a trumpet-shaped groove (5), and the trumpet-shaped groove (5) is connected to the through hole (3); The trumpet-shaped groove (5) and the T-shaped groove (4) are respectively arranged on two opposite sides of the through hole (3); The area of ​​the through hole (3) is much smaller than the area of ​​the wafer being inspected.

2. The bottom air curtain protection device for deep ultraviolet wafer defect detection according to claim 1, characterized in that: The cavity is communicated with a gas supply system of a wafer defect detection system.

3. The bottom air curtain protection device for deep ultraviolet wafer defect detection according to claim 1, characterized in that: The T-shaped groove (4) comprises a transverse groove (6) and a vertical groove (7); one end of the vertical groove (7) is connected to the middle position of the transverse groove (6), and the other end is connected to the through hole (3).

4. The bottom air curtain protection device for deep ultraviolet wafer defect detection according to claim 3, characterized in that: The width of the vertical groove (7) is the same as the width of the through hole (3).

5. The bottom air curtain protection device for deep ultraviolet wafer defect detection according to claim 1, characterized in that: The air inlet end of the trumpet-shaped groove (5) is connected to the through hole (3), and the air outlet end coincides with the edge of the air curtain member (2).

6. The bottom air curtain protection device for deep ultraviolet wafer defect detection according to claim 5, characterized in that: The width of the air inlet end of the trumpet-shaped groove (5) is the same as the width of the through hole (3).

7. The bottom air curtain protection device for deep ultraviolet wafer defect detection according to claim 1, characterized in that: The through hole (3) is in the shape of a rectangle.

8. The bottom air curtain protection device for deep ultraviolet wafer defect detection according to any one of claims 1 to 7, characterized in that: The overall thickness of the connecting piece (1) and the air curtain piece (2) is less than 15.0 mm, and the thickness of the air curtain piece (2) is less than 2.0 mm.

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