Electrode backboard structure capable of improving discharge stability and laser
By using impedance backplane made of positive or negative temperature coefficient thermoresistive material on the backplane of the laser electrode, the electric field distribution is regulated, and the filamentous discharge problem arises in excimer lasers under high frequency discharge conditions is solved, which significantly improves the discharge stability and laser performance.
Patent Information
- Application Number
- CN202311728687.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-15
- Publication Date
- 2025-06-17
AI Technical Summary
Excimer lasers are prone to uneven filamentary discharge under high-frequency discharge conditions, resulting in poor discharge stability and affecting the laser spot performance and equipment life.
A positive or negative impedance metal backplate made of a positive temperature coefficient thermoresistive material or a negative temperature coefficient thermoresistive material is used as an electrode backplate structure to regulate the electric field distribution of the electrode at high temperatures, thereby suppressing the occurrence of filamentous discharge.
It effectively suppresses uneven filamentous discharge, reduces electrode damage, and improves the discharge stability of the laser and controllability of performance indicators.
Smart Images
Figure CN120165286A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of lasers, and in particular, to an electrode backplane structure and a laser for improving discharge stability. Background Art
[0002] Currently, in the field of high-end lithography, due to its characteristics of high repetition rate, narrow line width, and large energy, high-repetition-rate excimer lasers are the absolutely dominant light sources applied in the field of semiconductor lithography.
[0003] For excimer lasers, the high-repetition-rate discharge stability has a very important impact on output laser spot index performance, discharge chamber and working gas life, etc. There are research reports that under high-repetition-rate discharge conditions, hot spot discharges will appear on the cathode surface of excimer lasers. The appearance of hot spot discharges will cause the initial uniform and stable glow discharge to evolve into non-uniform and less stable filamentary discharge. Therefore, how to suppress the less stable filamentary discharge is a problem that needs to be solved.
[0004] See Figure 1 As shown, in the initial stage of discharge, a uniform plasma 3, that is, a glow discharge region, will be generated between the cathode 11 and the anode 12. However, when the current density is high enough, hot spot discharges will randomly appear on the surface of the cathode 11, resulting in the generation of filamentary discharge 4.
[0005] Current research generally believes that the hot spots on the cathode 11 caused by high current density in the discharge plasma are the main reason for the discharge to transform from glow discharge 3 to filamentary discharge 4. When hot spot discharges appear on the surface of the cathode 11, the electron density in this local area will rapidly increase, thus triggering a filamentary discharge 4 channel for the cathode 11 and the anode 12 to conduct. The filamentary discharge 4 channel has the characteristics of small channel impedance and large current density compared with the adjacent discharge area, which will further promote the temperature rise of the local area of the cathode 11, and the hot spot discharges will be stronger, forming a positive feedback cycle of deterioration and may lead to the transition of arc discharge. Summary of the Invention
[0006] The purpose of the present invention is to provide an electrode backplane structure and a laser for improving discharge stability to solve at least one of the above technical problems existing in the prior art.
[0007] To solve the above technical problems, an electrode backplane structure for improving discharge stability provided by the present invention includes: an electrode in a laser discharge chamber; A metal backplane is laid on the back of the electrode; The metal backplane is a positive impedance backplane made of a positive temperature coefficient thermistor material; or, the metal backplane is a negative impedance backplane made of a negative temperature coefficient thermistor material.
[0008] Among them, the negative temperature coefficient thermistor material (NTC material) is a semiconductor ceramic made of two or more metal oxides such as manganese, copper, silicon, cobalt, iron, nickel, and zinc through processes such as thorough mixing, shaping, and sintering.
[0009] Among them, the positive temperature coefficient thermistor material (PTC material) is a material whose resistance increases with the increase in temperature. Most metal materials have the PTC effect. For example, platinum, nickel, molybdenum, etc.
[0010] Furthermore, the metal backplane has a uniform thickness in the width direction of the electrode.
[0011] Furthermore, the positive impedance backplane has the same length as the electrode; in the length direction of the electrode, the two ends of the positive impedance backplane are thick and the middle is thin.
[0012] Preferably, the bottom surface of the positive impedance backplane that abuts against the electrode is a plane; the shape of the back surface of the positive impedance backplane that faces away from the electrode in the vertical cross-section including the length direction of the electrode is a concave smooth arc.
[0013] Furthermore, the positive impedance backplane covers the entire back surface of the electrode; In the length direction of the electrode, the positive impedance backplane includes: an intermediate section in the middle and thickened sections at both ends; The thickness of the intermediate section is uniform; In the length direction of the electrode and in the direction from the middle to both ends, the thickness of the thickened section gradually increases. Preferably, the thickness of the thickened section gradually increases linearly.
[0014] Preferably, the thickness of the intermediate section is 0.05 - 0.5 mm; The maximum thickness of the thickened section is 0.1 mm - 3 mm; the length of the thickened section is 10 mm - 50 mm.
[0015] Furthermore, the shape of the positive impedance backplane in the vertical cross-section including the length direction of the electrode is triangular. Two triangular positive impedance backplanes are laid at both ends of the electrode. In the length direction of the electrode and in the direction from the middle to both ends, the thickness of the positive impedance backplane gradually increases.
[0016] Preferably, the maximum thickness of the triangular positive impedance backplane is 0.1 mm - 3 mm; in the length direction of the electrode, the length (bottom side length) of the triangular positive impedance backplane is 10 mm - 50 mm.
[0017] Among them, the length of the electrode is generally between 400 - 800 mm.
[0018] Further, the negative impedance backplane has the same length as the electrode; in the length direction of the electrode, both ends of the negative impedance backplane are thin and the middle is thick.
[0019] Preferably, the bottom surface of the negative impedance backplane that abuts against the electrode is a plane; the shape of the back surface of the negative impedance backplane facing away from the electrode in the vertical cross-section including the length direction of the electrode is a smooth convex arc.
[0020] Further, the negative impedance backplane covers the entire back surface of the electrode; In the length direction of the electrode, the negative impedance backplane includes: a middle part in the middle and thinning sections at both ends; The thickness of the middle part is uniform; In the length direction of the electrode and in the direction from the middle to both ends, the thickness of the thinning section gradually decreases. Preferably, the thickness of the thinning section decreases linearly.
[0021] Preferably, the thickness of the middle part is 0.1 mm - 3 mm; The thickness of the thickest end of the thinning section is equal to the thickness of the middle part, and the thickness of the thinnest end of the thinning section is 0.05 - 0.5 mm; the length of the thinning section is 10 mm - 50 mm.
[0022] Further, in the length direction, the negative impedance backplane is laid in the middle of the electrode, and no negative impedance backplane is provided at both ends of the electrode or a positive impedance backplane is provided.
[0023] Further, a conductive metal layer is laid on the back surface of the electrode; the metal backplane is arranged between the conductive metal layer and the electrode.
[0024] Further, the top surface of the conductive metal layer facing away from the electrode is a plane parallel to the top surface of the electrode.
[0025] The conductive metal layer is made of ordinary conductive metal materials such as brass or nickel-plated aluminum plate.
[0026] After adding the conductive metal layer, the thickness of the electrode can be made more uniform, so that the power supply energy can be applied to the cathode more uniformly. The positive temperature coefficient or negative temperature coefficient of the conductive metal layer is much smaller than the positive temperature coefficient or negative temperature coefficient of the metal backplane; preferably, the positive temperature coefficient or negative temperature coefficient of the metal backplane is more than 3 times that of the positive temperature coefficient or negative temperature coefficient of the conductive metal layer. Thus, the electric field distribution of the electrode at high temperature is regulated by using the metal backplane.
[0027] Further, the electrode is an anode or a cathode.
[0028] Preferably, the positive impedance backplane is arranged on the back of the cathode.
[0029] The second aspect of the present application discloses a laser using the above electrode backplane structure for improving discharge stability.
[0030] Adopting the above technical solution, the present invention has the following beneficial effects: An electrode backplane structure for improving discharge stability provided by the present invention effectively suppresses the occurrence, duration and intensity of non-uniform filamentary discharge 4, reduces the electrode damage caused by the excessive current intensity and long duration of filamentary discharge 4, improves the controllable parameters of the laser performance index, and especially improves the discharge stability of the discharge chamber. Description of the Drawings
[0031] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0032] Figure 1 It is the working principle diagram of the laser discharge in the prior art; Figure 2 Schematic diagram of the electrode backplane structure provided in Embodiment 1 of the present invention; Figure 3 Schematic diagram of the electrode backplane structure provided in Embodiment 2; Figure 4 Schematic diagram of the electrode backplane structure provided in Embodiment 3; Figure 5 Schematic diagram of the structure when the negative impedance backplane 22 and the positive impedance backplane 21 are used in combination in Embodiment 3; Figure 6 Schematic diagram of the electrode backplane structure provided in Embodiment 4; Figure 7 Schematic diagram of another embodiment structure of the electrode backplane in Embodiment 4.
[0033] Reference Signs: 3 - Glow discharge; 4 - Filamentary discharge; 5 - Conductive metal layer; 10 - Electrode; 11 - Cathode; 12 - Anode; 20 - Metal backplane; 21 - Positive impedance backplane; 21a - Thickened section; 21b - Intermediate section; 22 - Negative impedance backplane; 22a - Thinned section; 22b - Intermediate part. Detailed Embodiments
[0034] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0035] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is 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 thus should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.
[0036] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, 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 directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.
[0037] The following further explains the present invention in combination with specific embodiments.
[0038] Embodiment 1 As Figure 2 shown, an electrode backplane structure for improving discharge stability provided in this embodiment includes: an electrode 10 in a laser discharge cavity; a metal backplane 20 is laid on the back of the electrode 10; the metal backplane 20 is a positive impedance backplane 21 made of a positive temperature coefficient thermistor material; or, the metal backplane 20 is a negative impedance backplane 22 made of a negative temperature coefficient thermistor material. The metal backplane 20 has a uniform thickness in the width direction of the electrode 10.
[0039] Among them, the negative temperature coefficient thermistor material (NTC material) is a semiconductor ceramic made of two or more metal oxides such as manganese, copper, silicon, cobalt, iron, nickel, and zinc through processes such as sufficient mixing, molding, and sintering.
[0040] The positive temperature coefficient thermistor material (PTC material) is a material whose resistance increases with the increase in temperature. Most metal materials have the PTC effect. For example, platinum, nickel, molybdenum, etc.
[0041] Affected by the structure of the cathode 1, the electric field strength at the end of the electrode 10 is often relatively large. Therefore, the probability of filamentary discharge is higher, which will cause the end of the cathode 1 to be corroded first.
[0042] Preferably, in this embodiment, the shape of the positive impedance backplane 21 in the vertical cross-section including the length direction of the electrode 10 is triangular. Two triangular positive impedance backplanes 21 are laid at both ends of the electrode 10. Specifically, the positive impedance backplane 21 is laid at both ends of the cathode 21. In the length direction Y of the electrode 10 and in the direction from the middle to both ends, the thickness of the positive impedance backplane 21 gradually increases.
[0043] When the discharge in the plasma region develops to the filamentary discharge stage, the current density in the longitudinal path of the filamentary discharge will increase. The cathode 11 backplane introduced in this application has positive impedance characteristics, that is, when the current increases, the longitudinal voltage division and resistance at the local positions (specifically, both ends) of the cathode 11 will increase. Under the same input voltage, the increase in the resistance and voltage division of the local cathode 11 backplane will inhibit the further development of the filamentary discharge channel.
[0044] Preferably, the maximum thickness of the triangular positive impedance backplane 21 is 0.1 mm - 3 mm; in the length direction Y of the electrode 10, the length of the triangular positive impedance backplane 21, that is, the length of the base of the triangle, is 10 mm - 50 mm. And the length of the electrode 10 is generally between 400 - 800 mm.
[0045] Further preferably, a conductive metal layer 5 is laid on the back of the electrode 10 (i.e., the cathode 11); the metal backplane 20 (i.e., the positive impedance backplane 21) is arranged between the conductive metal layer 5 and the electrode 10.
[0046] The top surface of the conductive metal layer 5 facing away from the electrode 10 is a plane parallel to the top surface of the electrode 10. The conductive metal layer 5 is made of ordinary conductive metal materials such as copper.
[0047] After adding the conductive metal layer 5, the metal backplane 20 is combined with the conductive metal layer 5, and the structural design of the metal layer 5 fits well with the metal backplane 20, so that the total height of the two after fitting remains the same. Thus, the power supply energy can be applied to the cathode more evenly. The positive temperature coefficient or negative temperature coefficient of the conductive metal layer 5 is much smaller than the positive temperature coefficient or negative temperature coefficient of the metal backplane 20; preferably, the positive temperature coefficient or negative temperature coefficient of the metal backplane 20 is more than 3 times that of the positive temperature coefficient or negative temperature coefficient of the conductive metal layer 5. Thus, the electric field distribution of the electrode 10 at high temperature is regulated by using the metal backplane 20.
[0048] An electrode backplane structure for improving discharge stability provided by the present invention effectively suppresses the occurrence, duration, and intensity of non-uniform filamentary discharges, reduces the damage to the electrode 10 caused by excessive filamentary discharge current intensity and long duration, improves the controllable parameters of the laser performance index, and particularly improves the discharge stability of the discharge chamber.
[0049] Example 2 The electrode backplane structure for improving discharge stability disclosed in this embodiment is basically the same as that in Example 1, except that: See Figure 3 As shown, the positive impedance backplane 21 in this embodiment has the same length as the cathode 11; that is, the positive impedance backplane 21 covers the entire back of the cathode 11; in the length direction Y of the cathode 11, the two ends of the positive impedance backplane 21 are thick and the middle is thin.
[0050] Specifically, in the length direction Y of the cathode 11, the positive impedance backplane 21 includes: an intermediate section 21b in the middle and thickened sections 21a at both ends; The thickness of the intermediate section 21b is uniform and is arranged in the middle of the back of the cathode 11.
[0051] In the length direction Y of the cathode 11 and in the direction from the middle to both ends, the thickness of the thickened section 21a gradually increases. Preferably, the thickness of the thickened section 21a gradually increases linearly.
[0052] The thickness of the intermediate section 21b is 0.05 - 0.5 mm; the inner end of the thickened section 21a is the thinnest and has the same thickness as the intermediate section 21b; the thickness gradually increases towards both sides, and the maximum thickness at the outermost end is 0.1 mm - 3 mm; the length of the thickened section 21a is 10 mm - 50 mm.
[0053] Another alternative implementation is that the bottom surface of the positive impedance backplane 21 in contact with the cathode 11 is flat; the shape of the back surface of the positive impedance backplane 21 facing away from the cathode 11 in the vertical section including the length direction of the electrode 10 is a concave smooth arc, which can also achieve the purpose of being thin in the middle and thick at both ends.
[0054] The same as in Example 1, a conductive metal layer 5 is laid on the back of the cathode 11; the positive impedance backplane 21 is arranged between the conductive metal layer 5 and the electrode 10.
[0055] Example 3 The electrode backplane structure for improving discharge stability disclosed in this embodiment is basically the same as that in Example 1, except that: In this embodiment, the metal backplane 20 includes a negative impedance backplane 22. See Figure 4As shown, in this embodiment, the negative impedance backplane 22 is disposed on the back of the anode 12. The negative impedance backplane 22 has the same length as the anode 12; the negative impedance backplane 22 covers the entire back surface of the anode 12. In the length direction Y of the anode 12, both ends of the negative impedance backplane 22 are thin and the middle is thick.
[0056] Optionally, the bottom surface of the negative impedance backplane 22 in contact with the anode 12 is a plane; the shape of the back surface of the negative impedance backplane 22 facing away from the anode 12 in the vertical cross-section including the length direction of the electrode 10 is a smooth convex arc, so as to achieve the above-mentioned structure with thin ends and thick middle.
[0057] More preferably, in the length direction Y of the anode 12, the negative impedance backplane 22 includes: an intermediate portion 22b in the middle and thinning sections 22a at both ends; the thickness of the intermediate portion 22b is uniform; in the length direction Y of the anode 12 and in the direction from the middle to both ends, the thickness of the thinning section 22a gradually decreases. Preferably, the thickness of the thinning section 22a decreases linearly.
[0058] The thickness of the intermediate portion 22b is 0.1 mm - 3 mm; the thickness of the thickest end of the thinning section 22a is equal to the thickness of the intermediate portion 22b, and the thickness of the thinnest end of the thinning section 22a is 0.05 - 0.5 mm; the length of the thinning section 22a is 10 mm - 50 mm.
[0059] Similar to Embodiment 1, a conductive metal layer 5 is disposed on the back surface of the anode 12; the negative impedance backplane 22 is disposed between the conductive metal layer 5 and the anode 12.
[0060] The negative impedance backplane 22 can be separately disposed on the cathode 11 and / or the anode 12. Refer to Figure 5 As shown, the negative impedance backplane 22 can also be used in combination with the positive impedance backplane 21, and the two are respectively disposed on different cathodes 11 and anodes 12.
[0061] When the discharge in the plasma region develops to the filamentary discharge stage, the current density in the longitudinal path of the filamentary discharge will increase. The anode 12 backplane introduced in this application has negative impedance characteristics, that is, when the current increases, the longitudinal partial voltage and resistance of the local position (specifically the middle part) of the anode 12 will decrease. Under the same input voltage, the reduction of the resistance and partial voltage of the local cathode 11 backplane will inhibit the further development of the filamentary discharge channels at both ends thereof.
[0062] Embodiment 4 The electrode backplane structure for improving discharge stability disclosed in this embodiment is basically the same as that of Embodiments 1 - 3, and the differences are as follows: Refer to Figure 6As shown, in the length direction, the negative impedance backplane 22 is laid in the middle of the anode 12, and the negative impedance backplane 22 is not provided at both ends of the anode 12. Both ends of the negative impedance backplane 22 are smoothly transitioned to the anode 12.
[0063] See Figure 7 As shown, in the length direction, the negative impedance backplane 22 is laid in the middle of the cathode 11 and the anode 12, and the positive impedance backplane 21 is provided at both ends of the cathode 11 and the anode 12. A smooth transition is made between the positive impedance backplane 21 and the negative impedance backplane 22. Compared with the above-described embodiment, the impedance change in this embodiment is more obvious, and the occurrence probability of filamentary discharge can be further reduced.
[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. An electrode backplane structure for improving discharge stability, characterized in that, Comprising: An electrode (10) within the discharge cavity of a laser; A metal backplane (20) is laid on the back of the electrode (10); The metal backplane (20) is a positive impedance backplane (21) made of a positive temperature coefficient thermoresistive material; or, the metal backplane (20) is a negative impedance backplane (22) made of a negative temperature coefficient thermoresistive material.
2. The electrode backplane structure according to claim 1, characterized in that, The metal backplane (20) has a uniform thickness in the width direction of the electrode (10).
3. The electrode backplane structure according to claim 1, characterized in that, The positive impedance backplane (21) is the same length as the electrode (10); in the length direction of the electrode (10), the two ends of the positive impedance backplane (21) are thick and the middle is thin.
4. The electrode backplane structure according to claim 1, characterized in that, The bottom surface of the positive impedance backplane (21) that abuts against the electrode (10) is flat; the shape of the back surface of the positive impedance backplane (21) facing away from the electrode (10) in the vertical cross-section containing the length direction of the electrode (10) is a concave smooth arc.
5. The electrode backplane structure according to claim 1, characterized in that, The positive impedance backplane (21) covers the entire back surface of the electrode (10); In the length direction of the electrode (10), the positive impedance backplane (21) includes: a middle section (21b) in the middle and thickened sections (21a) at both ends; The thickness of the middle section (21b) is uniform; In the length direction of the electrode (10) and in the direction from the middle to both ends, the thickness of the thickened section (21a) gradually increases.
6. The electrode backplane structure according to claim 5, characterized in that, The thickness of the thickened section (21a) gradually increases linearly.
7. The electrode backplane structure according to claim 5, characterized in that, The thickness of the middle section (21b) is 0.05 - 0.5 mm; The maximum thickness of the thickened section (21a) is 0.1 mm - 3 mm; the length of the thickened section (21a) is 10 mm - 50 mm.
8. The electrode backplane structure according to claim 1, characterized in that, The shape of the positive impedance backplane (21) in the vertical cross-section containing the length direction of the electrode (10) is triangular, and two triangular positive impedance backplanes (21) are laid at both ends of the electrode (10). In the length direction of the electrode (10) and in the direction from the middle to both ends, the thickness of the positive impedance backplane (21) gradually increases.
9. The electrode backplane structure according to claim 8, characterized in that, The maximum thickness of the triangular positive impedance backplane (21) is 0.1 mm - 3 mm; in the length direction of the electrode (10), the length of the triangular positive impedance backplane (21) is 10 mm - 50 mm.
10. The electrode backplane structure according to claim 1, characterized in that, The negative impedance backplane (22) is the same length as the electrode (10); in the length direction of the electrode (10), the two ends of the negative impedance backplane (22) are thin and the middle is thick.