Cathode mounting structure, ion source and ion implantation equipment

Abstract

The utility model relates to the technical field of semiconductors, and provides a cathode mounting structure, an ion source and ion implantation equipment, and the cathode mounting structure comprises an arc chamber; a mounting hole for the cathode to pass through is formed in the arc chamber; the mounting hole is divided into a small-diameter section and a large-diameter section which are connected along the axial direction of the mounting hole; the small-diameter section is communicated with the outside of the arc chamber; one end of the large-diameter section is communicated with the small-diameter section, the other end of the large-diameter section is communicated with an inner cavity of the arc chamber, and the inner diameter of the end, communicated with the inner cavity of the arc chamber, of the large-diameter section is larger than that of the small-diameter section. According to the utility model, the cathode mounting structure is improved, so that the short circuit phenomenon caused by accumulation of products on the outer wall of the cathode is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductors, in particular to a cathode mounting structure, an ion source and ion implantation equipment. Background Art

[0002] Ion implantation is a crucial doping technique in modern integrated circuit manufacturing. It uses ion implantation equipment to accelerate ions and inject dopant elements into semiconductor wafers, altering their conductive properties and ultimately forming the desired device structure. Ion implantation equipment typically consists of an ion source, ion extraction and mass analyzer, an accelerator tube, a scanning system, a process chamber, and a high-vacuum system. The high-vacuum system creates a negative pressure environment in the process chamber. The ion source generates an ion beam, which is separated by ion extraction and mass analyzer. The ion beam is then accelerated by the accelerator tube and enters the process chamber to bombard the wafer surface, achieving ion implantation.

[0003] Ion implantation equipment mainly generates thermal electrons at the cathode, and generates plasma when the thermal electrons collide with the doping source gas in the arc chamber. The plasma is then drawn out by the potential energy difference and injected into the silicon wafer to complete the ion implantation.

[0004] Because the arc chamber must withstand high temperatures, it is typically constructed from a tungsten alloy to maintain a suitable chamber environment. However, the fluorine ions produced by the dissociation of the dopant source gas easily react with tungsten to form tungsten fluoride. Over time, this fluoride accumulates on the cathode's outer wall, causing it to swell and eventually contact the inner wall of the arc chamber, resulting in a short circuit. If a short circuit occurs, the machine must undergo maintenance and the ion source must be replaced before production can resume.

[0005] Therefore, based on the above technical problems, a cathode mounting structure, an ion source and an ion implantation device are needed to improve the cathode mounting structure so as to alleviate the short circuit phenomenon caused by the accumulation of products on the cathode outer wall. Utility Model Content

[0006] The purpose of the utility model is to provide a cathode mounting structure, an ion source and an ion implantation device, which improve the cathode mounting structure to alleviate the short circuit phenomenon caused by the accumulation of products on the cathode outer wall.

[0007] The utility model provides a cathode installation structure comprising: an arc chamber;

[0008] The arc chamber is provided with a mounting hole for the cathode to pass through;

[0009] The mounting hole is divided into a connected small diameter section and a large diameter section along its axial direction;

[0010] The small diameter section is in communication with the outside of the arc chamber;

[0011] One end of the large diameter section is connected to the small diameter section, and the other end of the large diameter section is connected to the inner cavity of the arc chamber. The inner diameter of the end of the large diameter section connected to the inner cavity of the arc chamber is larger than the inner diameter of the small diameter section.

[0012] Optionally, the small diameter section is a constant diameter section, the large diameter section is a variable diameter section, and the inner diameter of the large diameter section gradually increases from the side close to the small diameter section to the side away from the small diameter section along the axial direction of the mounting hole.

[0013] Optionally, in a cross section formed by cutting along the central axis of the mounting hole, the inner wall of the large-diameter section is a curved surface.

[0014] Optionally, the axial length of the mounting hole is L1, the axial length of the large diameter section is L2, and the ratio of L2 to L1 is 0.4 to 0.6.

[0015] And / or, the radius of the small-diameter section is 1 mm to 1.5 mm larger than the radius of the cathode to be installed in the installation hole.

[0016] Optionally, the curved surface has a concave structure.

[0017] Optionally, the curved surface is an arc surface.

[0018] Optionally, the center of the arc surface is located on the central axis of the mounting hole.

[0019] Optionally, the mounting hole is provided on a first side wall of the arc chamber, and the mounting hole is located at a center position of the first side wall along a first direction;

[0020] Along the first direction, the distance between the edge of the large diameter end of the large diameter segment and the edge of the first side wall is L3, and the distance between the edge of the small diameter segment and the edge of the first side wall is L4. The ratio of L3 to L4 is 0.4 to 0.6.

[0021] The utility model also provides an ion source, comprising the cathode mounting structure and the cathode;

[0022] The cathode is coaxially mounted in the mounting hole.

[0023] The utility model also provides an ion implantation device, which is equipped with the above-mentioned ion source.

[0024] In the present invention, the mounting hole comprises a small-diameter section and a large-diameter section. The large-diameter section has a larger inner diameter closer to the arc chamber. This increases the gap between the inner wall of the mounting hole and the outer wall of the cathode closer to the arc chamber, helping to store more product and thereby reducing short circuits caused by product accumulation on the outer wall of the cathode. Furthermore, the mounting hole retains a small-diameter section, which helps to minimize the minimum gap between the mounting hole and the cathode, thereby preventing leakage of dopant gas within the arc chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of a cathode installation according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the partial structure of the cathode installation of an embodiment of the present invention. Figure 1 ;

[0027] Figure 3 This is a schematic diagram of the partial structure of the cathode installation of an embodiment of the present invention. Figure 2 .

[0028] Among them, in the accompanying drawings:

[0029] 10-arc chamber; 11-mounting hole; 111-small diameter section; 112-large diameter section;

[0030] 20-cathode. DETAILED DESCRIPTION

[0031] The cathode mounting structure, ion source, and ion implantation apparatus proposed in the present invention are further described in detail below, with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention.

[0032] As used in the present invention, the singular forms "a", "an", and "the" include plural objects, the term "or" is generally used to include the meaning of "and / or", the term "several" is generally used to include the meaning of "at least one", and the terms "at least two" or "a plurality" are generally used to include the meaning of "two or more". In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features. In addition, as used in the present invention, "installed", "connected", "connected", and one element is "set" on another element should be understood in a broad sense, usually only indicating that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the connection, coupling, cooperation or transmission between the two elements can be direct or indirect through an intermediate element, and cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, one element can be in any orientation such as inside, outside, above, below or on one side of another element, unless the content clearly indicates otherwise. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, directional terms such as above, below, up, down, upward, downward, left, right, etc. are used relative to the exemplary embodiments as they are shown in the figures, with the upward or upper direction toward the top of the corresponding figure, and the downward or lower direction toward the bottom of the corresponding figure.

[0033] This embodiment provides a cathode mounting structure, comprising: an arc chamber 10;

[0034] The arc chamber 10 is provided with a mounting hole 11 for the cathode 20 to pass through; the cathode 20 is used to generate thermal electrons. Doping gas is introduced into the arc chamber 10, and the electrons generated by the cathode 20 are emitted toward the arc chamber 10. After these high-energy thermal electrons collide with the doping source gas introduced into the arc chamber 10, the doping source gas will be dissociated and positively and negatively charged ions will be generated.

[0035] The mounting hole 11 is provided for a portion of the cathode 20 to pass through into the arc chamber 10. The mounting hole 11 is coaxial with the cathode 20. The gap between the outer surface of the cathode 20 and the inner wall of the mounting hole 11 should be small to ensure that the doping gas in the arc chamber 10 does not leak.

[0036] Since the arc chamber needs to withstand high temperatures, the arc chamber material usually contains tungsten alloy to meet the chamber environment. However, the fluorine ions generated after the doping source gas dissociates easily react with tungsten to produce tungsten fluoride products. This product will gradually accumulate on the part of the cathode 20 located in the arc chamber 10 (for example, on the cathode 20). Figure 1If the gap between the outer peripheral surface of the cathode 20 and the inner wall of the mounting hole 11 is small, the product accumulated outside the cathode 20 can easily cause the outer peripheral surface of the cathode 20 to connect and contact with the inner wall of the mounting hole 11, resulting in a short circuit.

[0037] In order to avoid the above short circuit phenomenon, the present embodiment further improves the structure of the mounting hole 11. The mounting hole 11 includes a coaxial small diameter section 111 and a large diameter section 112.

[0038] The small-diameter section 111 is in communication with the outside of the arc chamber 10 . In this embodiment, the small-diameter section 111 is configured as a constant-diameter section, that is, the inner diameter of the small-diameter section 111 is constant.

[0039] One end of the large diameter section 112 ( Figure 1 The left end of the large diameter section 112 is connected to the small diameter section 111. The end of the large diameter section 112 has the same inner diameter as the small diameter section 111; the other end of the large diameter section 112 ( Figure 1 The right end in FIG) is connected to the inner cavity of the arc chamber 10, and the inner diameter of the end portion of the large-diameter section 112 connected to the inner cavity of the arc chamber 10 is greater than the inner diameter of the small-diameter section 111.

[0040] In this embodiment, the large diameter section 112 is configured as a variable diameter section, which is arranged along the axial direction of the mounting hole 11 from the side close to the small diameter section 111 to the side away from the small diameter section 111 (i.e., Figure 1 (from left to right in the figure), the inner diameter of the large diameter section 112 gradually increases.

[0041] Combine Figure 2 and Figure 3 As shown, the inner diameter of the large-diameter section 112 increases as it approaches the arc chamber 10. This increases the gap between the inner wall of the mounting hole 11 and the outer wall of the cathode 20 as it approaches the arc chamber 10, helping to store more product and thereby reducing short circuits caused by product accumulation on the cathode outer wall. Furthermore, the mounting hole 11 also retains a small-diameter section 111, which helps to minimize the minimum gap between the mounting hole 11 and the cathode 20, thereby preventing leakage of dopant gas within the arc chamber 10.

[0042] In this embodiment, the small-diameter section 111 has a constant diameter structure, while the large-diameter section 112 has a variable diameter structure. In other alternative embodiments, both the small-diameter section 111 and the large-diameter section 112 can be configured as constant diameter structures, i.e., the mounting hole 11 as a whole has a stepped hole structure. Alternatively, the inner diameters of the small-diameter section 111 and the large-diameter section 112 can be adaptively adjusted based on actual usage requirements.

[0043] Combine Figure 3As shown, in this embodiment, the inner wall of the large-diameter section 112 is a curved surface in a cross section formed along the central axis of the mounting hole 11. By setting the curvature of the curved surface, the gap between the cathode 20 and the inner wall of the mounting hole 11 at different axial positions can be more flexibly adjusted, thereby enabling more precise distance control.

[0044] Combine Figure 3 As shown, the curved surface has a concave structure. The concave structure helps to provide a larger accommodation space between the large diameter section 112 of the mounting hole 11 and the cathode 20 to accommodate more products, further improving the short circuit phenomenon caused by the accumulation of products on the cathode 20.

[0045] Furthermore, in this embodiment, the curved surface is an arc surface, the center of which is located on the central axis of the mounting hole 11. Since the cathode 20 and the mounting hole 11 are coaxially arranged, the center B of the arc surface is located on the central axis of the cathode 20.

[0046] Combine Figure 3 As shown, the position of the center B of the arc surface almost determines the radius R3 of the arc surface. By limiting the size of R3 and combining the position of the area A, the position where the product is easily accumulated on the cathode 20 and the transition position between the small diameter section 111 and the large diameter section 112 can be controlled ( Figure 3 The relative position relationship of position C).

[0047] In this embodiment, the center of circle B is also located on the inner end surface of the cathode 20. By setting the position of the center of circle B relative to the cathode 20, a reasonable distance is maintained between the position on the cathode 20 where the product is likely to accumulate and the transition position between the small diameter section 111 and the large diameter section 112. This allows the accumulated product on the cathode to be kept away from the small diameter section 111, further improving the short circuit phenomenon caused by the accumulated product on the cathode 20.

[0048] In other alternative embodiments, the center B may not be located on the inner end surface of the cathode 20 , and it only needs to be located on the central axis of the mounting hole 11 .

[0049] Further, combined Figure 3 As shown, in this embodiment, the axial length of the mounting hole 11 is L1, the axial length of the large diameter section 112 is L2, and the ratio of L2 to L1 is 0.4 to 0.6. For example, the ratio of L2 to L1 is set to 0.5. This ratio ensures that the large diameter section 112 forms a larger space for accommodating the accumulated product. On the other hand, a smaller gap exists between the small diameter section 111 and the cathode 20. By setting the length of the small diameter section 111, a better sealing effect is ensured. Moreover, the setting of the ratio of L2 to L1 also takes into account the local structural strength of the opening of the arc chamber 10.

[0050] Furthermore, the radius R2 of the small-diameter section 111 is 1 mm to 1.5 mm larger than the radius R1 of the cathode 20 to be installed in the mounting hole 11. For example, the radius R2 is 1.1 mm or 1.2 mm larger than the radius R1. This size limitation not only facilitates the installation of the cathode 20, but also helps to seal the cathode 20 with the mounting hole 11.

[0051] Please continue to refer to Figures 1 to 3 As shown, the mounting hole 11 is provided on the first side wall 12 of the arc chamber 10. In this embodiment, the arc chamber 10 is a rectangular structure having a rectangular inner cavity. The first side wall 12 is one side of the arc chamber 10 along the length direction and is rectangular.

[0052] The mounting hole 11 is located at the center of the first side wall 12 along the first direction a; wherein the first direction a corresponds to the height direction of the arc chamber 10, and the first direction a corresponds to the length direction of one side of the first side wall 12, and the horizontal direction of the arc chamber 10 corresponds to its length direction.

[0053] Along the first direction a, the distance between the edge of the large diameter end of the large diameter section 112 and the edge of the first side wall 12 is L3, and the distance between the edge of the small diameter section 111 and the edge of the first side wall 12 is L4. The ratio of L3 to L4 is 0.4 to 0.6, and can be set to 0.5, for example. By setting L3 and L4, the mounting hole 11 is adapted to the size of the first side wall 12, and the first side wall 12 is adapted to the existing arc chamber 10, while also ensuring good structural strength of the side wall.

[0054] In this embodiment, an ion source is further provided, comprising the cathode mounting structure described above and a cathode 20 , wherein the cathode 20 is coaxially mounted in the mounting hole 11 .

[0055] The ion source further includes components such as a filament, a first power supply unit, a second power supply unit and a third power supply unit.

[0056] The cathode 20 is cylindrical and contains a chamber extending from one end of the cathode 20 outside the arc chamber 10. A filament is mounted within the chamber of the cathode 20, with its ends connected to the positive and negative terminals of a first power supply unit. The positive terminal of a second power supply unit is connected to the cathode 20, while its negative terminal is connected to the filament. A third power supply unit has a positive terminal connected to the arc chamber 10, while its negative terminal is connected to the cathode 20.

[0057] An intermediate rod is also connected to the cavity of the cathode 20 and extends through the open end of the cathode 20 to fix the cathode.

[0058] The arc chamber 10 further has an air inlet and an air outlet. The air inlet is used to introduce doping gas, and the air outlet is used to allow the gas in the arc chamber 10 to flow out.

[0059] In this embodiment, the first power supply unit provides current to the filament, raising its temperature. When the filament's temperature reaches a certain level, it begins to generate thermal electrons. The second power supply unit connects the filament to the cathode, generating a fixed-direction electric field E between the filament and the cathode. This causes the thermal electrons generated by the filament to travel along the electric field toward the cathode and collide with it. After being struck by the thermal electrons, the cathode's temperature rises and more thermal electrons are generated. The third power supply unit connects the arc chamber to the cathode, generating a fixed-direction accelerating electric field within the arc chamber. When the thermal electrons generated by the cathode are attracted by the accelerating electric field, they become high-energy thermal electrons and are emitted toward the arc chamber. These high-energy thermal electrons collide with the dopant source gas introduced into the arc chamber, causing the dopant source gas to dissociate and generate positively and negatively charged ions for subsequent ion doping steps.

[0060] The ion source in this embodiment differs from the conventional ion source in that the cathode mounting structure is different, and the remaining structures are consistent with the conventional ion source. The specific structure and working principle of the ion source are prior art and will not be described in detail here.

[0061] In this embodiment, an ion implantation device is also provided, and the ion implantation device is equipped with the above-mentioned ion source.

[0062] The ion implantation equipment also includes an ion extraction and mass analyzer, an accelerator tube, a scanning system, a process chamber, and a high vacuum system. The process chamber is provided with a placement position for wafers, and the wafer to be doped is placed on the placement position. The high vacuum system is used to form a negative pressure environment in the process chamber. The ion source generates an ion beam and separates impurity ions through ion extraction and a mass analyzer. The ion beam is then accelerated by the accelerator tube to enter the process chamber and bombard the wafer surface to achieve ion implantation.

[0063] The difference between the above ion implantation device and the existing ion implantation device lies in the difference in the cathode mounting structure. The other components are consistent with the existing ion implantation device. The structure and principle of the ion implantation device are existing technology and will not be repeated here.

[0064] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0065] The above description is only a description of the preferred embodiment of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A cathode mounting structure, characterized in that: include: Arc chamber; The arc chamber is provided with a mounting hole for the cathode to pass through; The mounting hole is divided into a connected small diameter section and a large diameter section along its axial direction; The small diameter section is in communication with the outside of the arc chamber; One end of the large diameter section is connected to the small diameter section, and the other end of the large diameter section is connected to the inner cavity of the arc chamber. The inner diameter of the end of the large diameter section connected to the inner cavity of the arc chamber is larger than the inner diameter of the small diameter section.

2. The cathode mounting structure according to claim 1, wherein: The small diameter section is a constant diameter section, the large diameter section is a variable diameter section, and the inner diameter of the large diameter section gradually increases from the side close to the small diameter section to the side away from the small diameter section along the axial direction of the mounting hole.

3. The cathode mounting structure according to claim 2, wherein: In a cross section formed by cutting along the central axis of the mounting hole, the inner wall of the large-diameter section is a curved surface.

4. The cathode mounting structure according to claim 1 or 2, wherein: The axial length of the mounting hole is L1, the axial length of the large diameter section is L2, and the ratio of L2 to L1 is 0.4 to 0.6; And / or, the radius of the small-diameter section is 1 mm to 1.5 mm larger than the radius of the cathode to be installed in the installation hole.

5. The cathode mounting structure according to claim 3, wherein: The curved surface has a concave structure.

6. The cathode mounting structure according to claim 5, wherein: The curved surface is an arc surface.

7. The cathode mounting structure according to claim 6, wherein: The center of the arc surface is located on the central axis of the mounting hole.

8. The cathode mounting structure according to claim 2, wherein: The mounting hole is provided on the first side wall of the arc chamber, and the mounting hole is located at the center of the first side wall along the first direction; Along the first direction, the distance between the edge of the large diameter end of the large diameter segment and the edge of the first side wall is L3, and the distance between the edge of the small diameter segment and the edge of the first side wall is L4. The ratio of L3 to L4 is 0.4 to 0.

6.

9. An ion source, characterized in that comprising the cathode mounting structure and the cathode according to any one of claims 1 to 8; The cathode is coaxially mounted in the mounting hole.

10. An ion implantation device, characterized in that: The ion implantation device is equipped with the ion source according to claim 9.

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