Variable beam electron beam exposure device and exposure method

Abstract

The invention discloses a variable beam electron beam exposure device and an exposure method. The device comprises an exposure cavity, an optical column and a control unit, a movable workpiece table is placed in the exposure cavity; the optical column comprises an electron gun, a lens, a beam gate, a shaping deflector, a sub deflector, a main deflector, a beam gate diaphragm and a shaping diaphragm; the electron gun is used for emitting electron beams; the beam gate is used for opening and closing the electron beam; the shaping deflector is used for changing the impact position of the electron beam on the shaping diaphragm so as to shape the cross section of the light beam into a preset shape; the control unit comprises a constant current source, a PLC, an upper computer, a deflection control circuit and a pattern generator. The constant current source is used for controlling various lenses to focus, amplify or shrink the electron beam; and the deflection control circuit is used for receiving a signal which is transmitted from the upper computer to the pattern generator and is converted into an analog signal, and generating a driving signal to drive a corresponding deflector. The method has the advantages of high deflection precision and the like.

Description

Technical Field

[0001] The present invention mainly relates to the field of electron beam technology, and in particular to a variable shaped beam electron beam exposure device and an exposure method. Background Art

[0002] Deformable electron beam exposure machine is mainly used in the field of micro-nano processing. Its biggest features are extremely high resolution, short production cycle, and easy modification. Therefore, it is widely used in the production of photomasks and X-ray masks. It has become the main means of making masks in the microelectronics industry. On the other hand, the electron beam exposure system can achieve extremely high overlay accuracy using mark detection technology, so it can directly draw on the wafer, that is, directly manufacture devices on the wafer without a mask. Therefore, it is used in the development of new devices and new integrated circuits and the production of small batches of devices and integrated circuits.

[0003] In addition, the working process of the deformable electron beam exposure machine is that the electron gun emits electrons, and the electron beam is shaped into the required shape through the forming light path, and then the deflector deflects the electron beam to the position of the corresponding workpiece to be exposed, and then the beam gate is switched to realize the exposure of the area, and then it moves to the next area, repeating the above steps until the entire board is completed. It can be seen that the speed of the beam gate switch directly affects the exposure efficiency.

[0004] In the current design, the beam gate generally includes a pair of opposing electrodes that are opposite to each other across a gap through which the charged particle beam passes. In addition, the shaping deflector and the main deflector and auxiliary deflector used for beam scanning each include multiple pairs of opposing electrodes, each pair of opposing electrodes being opposite to each other across the air gas through which the charged particle beam passes. These opposing electrodes are usually made of pure metal materials. When a high-frequency voltage (e.g., 1 GHz) is applied to these opposing electrodes, eddy currents are generated in the electrodes. The magnetic field generated by the eddy currents causes undesirable changes in the deflection angle and direction of the electron beam (called "beam drift"), thereby reducing the deflection accuracy. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the present invention provides a variable shaped beam electron beam exposure device and an exposure method with high deflection accuracy.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0007] A variable shaped beam electron beam exposure device, comprising an exposure chamber, an optical column and a control unit;

[0008] The optical column is located at the top of the exposure chamber; a movable workpiece table is placed in the exposure chamber;

[0009] The optical column comprises an electron gun, a lens, a beam gate, a shaping deflector, a sub-deflector, a main deflector, a beam gate aperture and a shaping aperture; the electron gun is used to emit an electron beam; the beam gate is used to realize the opening and closing of the electron beam; the shaping deflector is used to change the impact position of the electron beam on the shaping aperture, so that part of the electron beam is blocked by the edge of the shaping aperture opening, so as to shape the cross section of the light beam into a predetermined shape;

[0010] The control unit includes a constant current source, a PLC, a host computer, a deflection control circuit and a pattern generator;

[0011] The constant current source is used to control various lenses to focus, magnify or reduce the electron beam to obtain a standard electron beam;

[0012] The deflection control circuit is used to receive the signal after the graphic data transmitted from the host computer to the graphic generator is converted into an analog signal, and generate a corresponding drive signal to drive the corresponding deflector, including outputting an open or close signal to the beam gate to achieve the purpose of switching the electron beam, and outputting corresponding data to the shaping deflector to shape the electron beam into a preset shape, and applying a corresponding drive signal to the main sub-field to enable the electron beam to expose the corresponding position of the workpiece.

[0013] As a further improvement of the above technical solution:

[0014] The beam gate includes a rod-shaped inner electrode and a cylindrical outer electrode surrounding the inner electrode, so that an air gap is formed between the inner electrode and the outer electrode for the electron beam to pass through.

[0015] The inner electrode and the outer electrode both include a substrate and an electrode film, and the electrode film is located on the surface of the substrate.

[0016] The electrode film is deposited on the surface of the substrate of the non-conductive material by vacuum deposition or sputtering.

[0017] The non-conductive material is aluminum oxide or ceramic.

[0018] The lower end of the inner electrode is electrically connected to the lower end of the outer electrode through a resistor; the upper ends of the inner electrode and the outer electrode are connected to a blanking amplifier, the central conductor and the shielding layer of the coaxial cable are respectively connected to the inner electrode and the outer electrode, and the current flows from the inner electrode to the outer electrode through the resistor to deflect the electron beam.

[0019] It also includes a position detection unit for measuring the position of the workpiece stage, which emits a laser and measures the position of the workpiece through a reflector installed on the workpiece stage, and then uploads the position information to the graphic generator. The graphic generator makes corresponding compensation according to the actual position of the workpiece W to calibrate the exposure data.

[0020] The exposure chamber 1 is equipped with a height detection unit for detecting the height of the exposure position of the workpiece W, and then uploading the data to the pattern generator. The pattern generator compensates the exposure data of the area accordingly based on the height data.

[0021] The present invention also discloses an exposure method based on the variable shaped beam electron beam exposure device as described above, comprising the steps of:

[0022] When exposing a pattern on the workpiece W, a writing operation is first performed on a frame area defined on the workpiece W while the workpiece stage continuously moves in one of the X and Y directions, wherein the frame area has a strip shape corresponding to the deflection width of the main deflector relative to the electron beam B; after writing is completed on the frame area, the workpiece stage moves one step in the Y direction, and then a writing operation is performed on the next frame area while the workpiece stage continuously moves in one of the X and Y directions, and continuously moves in the X direction, and this process is repeated to write on the entire surface of the workpiece W.

[0023] As a further improvement of the above technical solution:

[0024] Each frame area is divided into a plurality of subfield areas arranged in a matrix manner; when writing on the frame area, the electron beam is positioned in each subfield area in the frame area by the main deflector, and then scanned to each writing position in the subfield area by the sub-deflector, and at the same time the beam gate intermittently prevents the electron beam B from irradiating the workpiece W; at this time, the electron beam B is shaped into a predetermined shape for each writing position by the shaping deflector, and the workpiece W is irradiated at each writing position with the electron beam B, thereby writing the desired pattern on each subfield area.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] The variable shaped beam electron beam exposure device of the present invention,

[0027] The substrates of the inner electrode and the outer electrode of the present invention are respectively non-conductive materials, so the eddy currents generated in these electrodes can prevent the inner electrode and the outer electrode from being offset even when a high-frequency signal is applied to the electrodes; together with the impedance matching between the cable and the electrode, it ensures that a high deflection accuracy can be maintained even at high frequencies (e.g. 0.5 GHz).

[0028] The electrode films of the present invention are formed by vacuum deposition or sputtering, and the surfaces of the electrode films are clean and free of any pollutants, thereby effectively preventing beam drift. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a topological structure diagram of the variable shaped beam electron beam exposure device in an embodiment of the present invention.

[0030] Figure 2It is a longitudinal cross-sectional view of a coaxial beam brake according to an embodiment of the present invention.

[0031] Figure 3 FIG. 1 is a cross-sectional view of a coaxial beam brake according to an embodiment of the present invention.

[0032] Description of the drawings: 1. Exposure chamber; 2. Optical column; 21. Electron gun; 22. Lens; 23. Beam gate; 231. Inner electrode; 231a. Inner substrate; 231b. Inner electrode film; 232. Outer electrode; 232a. Outer substrate; 232b. Outer electrode film; 233. Resistor; 234. Coaxial cable; 234a. Center conductor; 234b. Shielding layer; 235. Connector; 24. Shaping deflector; 25. Sub-deflector; 26. Main deflector; 27. Beam gate aperture; 28. Shaping aperture; 3. Workpiece stage; 4. Constant current source; 5. PLC; 6. Host computer; 7. Deflection control circuit; 8. Pattern generator; 9. Height detection unit; 10. Position detection unit. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0034] like Figure 1 As shown, the variable shaped beam electron beam exposure device provided by the embodiment of the present invention comprises an exposure chamber 1 and an optical column 2; the optical column 2 is arranged on the top of the exposure chamber 1 and extends upward therefrom; a workpiece stage 3 movable in the vertical X and Y directions is placed in the exposure chamber 1, and a workpiece W is placed on the workpiece stage 3; wherein the workpiece W is a mask to be exposed;

[0035] The optical column 2 includes an electron gun 21, various lenses 22, a beam gate 23 for switching the electron beam, a shaping deflector 24, a sub-deflector 25, a main deflector 26, a beam gate aperture 27 and a shaping aperture 28;

[0036] The beam gate 23 can realize the opening and closing of the electron beam; when the beam gate 23 is opened, the beam gate 23 allows the electron beam B to pass straight through the opening of the beam gate aperture 27 to expose the workpiece W; when the beam gate 23 is closed, the beam gate 23 deflects the electron beam B to hit the beam gate aperture 27 outside its opening, thereby preventing the electron beam B from irradiating the workpiece W.

[0037] Furthermore, the shaping deflector 24 changes the impingement position of the electron beam B on the shaping aperture 28 so that part of the electron beam B is blocked by the edge of the opening of the shaping aperture 28 to shape the cross section of the beam into a predetermined shape.

[0038] The above-mentioned electron optical column 2 is controlled by a constant current source 4, a PLC 5, a deflection control circuit 7 and a pattern generator 8. The constant current source 4 controls various lenses (mainly magnetic lenses in this case) to focus, enlarge or reduce the electron beam and finally obtain an electron beam that meets the requirements. The deflection control circuit 7 is used to receive the signal after the graphic data transmitted from the host computer 6 to the pattern generator 8 is converted into an analog signal, and generate a corresponding drive signal to drive the corresponding deflector, including outputting an on or off signal to the beam gate 23 to achieve the purpose of switching the electron beam; and outputting corresponding data to the shaping deflector 24 to shape the electron beam into a pre-set shape, and applying a corresponding drive signal to the main sub-field so that the electron beam B exposes the corresponding position of the workpiece W.

[0039] It also includes a workpiece stage position detection unit 10 for measuring the X and Y positions of the workpiece stage 3, which can emit laser and then measure the position of the workpiece W through a reflector installed on the workpiece stage 3 (not marked here, the installation position can be selected according to actual conditions), and then upload the position information to the graphic generator 8. The graphic generator 8 makes corresponding compensation according to the actual position of the workpiece W to calibrate the exposure data.

[0040] The exposure chamber 1 is provided with a height detection unit 9 for detecting the height of the exposure position of the workpiece W, and then uploading the data to the pattern generator 8. The pattern generator 8 compensates the exposure data of the area accordingly based on the height data.

[0041] The beam gate 23 is a coaxial type, including a rod-shaped inner electrode 231 and a cylindrical outer electrode 232 surrounding the inner electrode 231, so that an air gap is formed between the inner electrode 231 and the outer electrode 232 for the electron beam B to pass through. Figure 2 As shown. The lower end of the inner electrode 231 is electrically connected to the lower end of the outer electrode 232 through the resistor 233. The upper ends of the inner electrode 231 and the outer electrode 232 are connected to the blanking amplifier, the central conductor 234a (or signal line) and the shielding layer 234b (or ground line) of the coaxial cable 234 are connected to the inner electrode 231 and the outer electrode 232 respectively, and the current flows from the inner electrode 231 to the outer electrode 232 through the resistor 233, so that the electron beam B is deflected. Figure 2 In the figure, 235 is a connector.

[0042] When the deflector is working, TEM mode electromagnetic waves propagate between the inner electrode 231 and the outer electrode 232. Therefore, the phase velocity and group velocity of the electromagnetic field generated in the deflector are independent of the frequency, so that the beam gate 23 has a constant characteristic impedance independent of the frequency of the applied signal. As a result, the characteristic impedance of the inner electrode 231 and the outer electrode 232 can be equal to the characteristic impedance of the cable 234 at high frequencies.

[0043] In addition, if Figure 2 and Figure 3As shown, the inner electrode 231 is formed by forming an inner electrode film 231b of a metal (e.g., gold) on the surface of an inner substrate 231a of a non-conductive material (e.g., alumina, ceramic, etc.) by vacuum deposition or sputtering. The outer electrode 232 is formed by forming an outer electrode film 232b of a metal (e.g., gold) on the surface of an outer substrate 232a of a non-conductive material (e.g., alumina, ceramic, etc.) by vacuum deposition or sputtering. Therefore, since the substrates (inner substrate 231a and outer substrate 232a) of the inner electrode 231 and the outer electrode 232 are respectively non-conductive materials, eddy currents are generated in these electrodes, and the displacement of the inner electrode 231 and the outer electrode 232 can be prevented even when a high-frequency signal is applied to the electrodes. This feature, together with the impedance matching between the above-mentioned cable and the electrode, ensures that a high deflection accuracy can be maintained even at high frequencies (e.g., 0.5 GHz).

[0044] The electrode films are formed by vacuum deposition or sputtering methods. The surfaces of these electrode films are clean and free of any contaminants, thereby effectively preventing beam drift (for example, the electrode films can be formed by electroplating, but the surface of the electrode films may be contaminated by materials other than the electrode film material in the plating solution, and may also be contaminated in the cleaning process after the electroplating process. These contaminants will cause beam drift).

[0045] The embodiment of the present invention further provides an exposure method based on the variable shaped beam electron beam exposure device as described above, comprising the steps of:

[0046] When exposing a pattern on the workpiece W, a writing operation is first performed on a frame area defined on the workpiece W while the workpiece stage 3 is continuously moved in one of the X and Y directions (e.g., the X direction), wherein the frame area has a stripe shape corresponding to the deflection width of the main deflector 26 relative to the electron beam B. After writing is completed on the frame area, the workpiece stage 3 moves one step in the Y direction, and then a writing operation is performed on the next frame area while the workpiece stage 3 is continuously moved in one of the X and Y directions (e.g., the X direction). The process is repeated to write on the entire surface of the workpiece W while continuously moving in the X direction.

[0047] It should be noted that each frame area is divided into a plurality of subfield areas arranged in a matrix. When writing on the frame area, the electron beam B is positioned in each subfield area in the frame area by the main deflector 26, and then scanned to each writing position in the subfield area by the subdeflector 25, while the beam gate 23 intermittently prevents the electron beam B from irradiating the workpiece W. At this time, the electron beam B is shaped into a predetermined shape for each writing position by the shaping deflector 24, and the workpiece W is irradiated with the electron beam B at each writing position, thereby writing the desired pattern on each subfield area.

[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. A variable shaped beam electron beam exposure device, characterized in that: It comprises an exposure chamber (1), an optical column (2) and a control unit; a movable workpiece table (3) is placed in the exposure chamber (1); The optical column (2) comprises an electron gun (21), a lens (22), a beam gate (23), a shaping deflector (24), a sub-deflector (25), a main deflector (26), a beam gate aperture (27) and a shaping aperture (28); the electron gun (21) is used to emit an electron beam; the beam gate (23) is used to realize the opening and closing of the electron beam; the shaping deflector (24) is used to change the impact position of the electron beam on the shaping aperture (28), so that part of the electron beam is blocked by the edge of the opening of the shaping aperture (28), so as to shape the cross section of the light beam into a predetermined shape; The control unit comprises a constant current source (4), a PLC (5), a host computer (6), a deflection control circuit (7) and a pattern generator (8); The constant current source (4) is used to control various lenses to focus, magnify or reduce the electron beam to obtain a standard electron beam; The deflection control circuit (7) is used to receive the signal converted from the graphic data transmitted from the host computer (6) to the graphic generator (8) into an analog signal, generate a corresponding driving signal to drive the corresponding deflector, including outputting an on or off signal to the beam gate (23) to achieve the purpose of switching the electron beam, and outputting corresponding data to the shaping deflector (24) to shape the electron beam into a preset shape, and applying a corresponding driving signal to the main sub-field to enable the electron beam to expose the corresponding position of the workpiece.

2. The variable shaped beam electron beam exposure device according to claim 1, characterized in that: The beam gate (23) comprises a rod-shaped inner electrode (231) and a cylindrical outer electrode (232) surrounding the inner electrode (231), so that an air gap is formed between the inner electrode (231) and the outer electrode (232) for the electron beam to pass through.

3. The variable shaped beam electron beam exposure device according to claim 2, characterized in that: The inner electrode (231) and the outer electrode (232) both include a substrate and an electrode film, and the electrode film is located on the surface of the substrate.

4. The variable shaped beam electron beam exposure device according to claim 3, characterized in that: The electrode film is deposited on the surface of the substrate of the non-conductive material by vacuum deposition or sputtering.

5. The variable shaped beam electron beam exposure device according to claim 4, characterized in that: The non-conductive material is aluminum oxide or ceramic.

6. The variable shaped beam electron beam exposure device according to any one of claims 2 to 5, characterized in that: The lower end of the inner electrode (231) is electrically connected to the lower end of the outer electrode (232) via a resistor (233); the upper ends of the inner electrode (231) and the outer electrode (232) are connected to a blanking amplifier, the central conductor (234a) and the shielding layer (234b) of the coaxial cable (234) are respectively connected to the inner electrode (231) and the outer electrode (232), and the current flows from the inner electrode (231) to the outer electrode (232) via the resistor (233), thereby deflecting the electron beam.

7. The variable shaped beam electron beam exposure device according to any one of claims 1 to 5, characterized in that: It also includes a position detection unit (10) for measuring the position of the workpiece stage (3), wherein the position detection unit (10) emits laser light, measures the position of the workpiece through a reflector mounted on the workpiece stage (3), and then uploads the position information to a pattern generator (8), which makes corresponding compensation according to the actual position of the workpiece to calibrate the exposure data.

8. The variable shaped beam electron beam exposure device according to any one of claims 1 to 5, characterized in that: The exposure chamber (1) is provided with a height detection unit (9) for detecting the height of the position of the workpiece to be exposed, and then uploading the data to the pattern generator (8). The pattern generator (8) compensates the exposure data of the area accordingly based on the height data.

9. An exposure method based on the variable shaped beam electron beam exposure device according to any one of claims 1 to 8, characterized in that: Includes steps: When exposing a pattern on a workpiece W, a writing operation is first performed on a frame area defined on the workpiece W, while the workpiece stage (3) continuously moves in one of the X and Y directions, wherein the frame area has a strip shape corresponding to the deflection width of the main deflector (26) relative to the electron beam B; after writing is completed on the frame area, the workpiece stage (3) moves one step in the Y direction, and then a writing operation is performed on the next frame area, while the workpiece stage (3) continuously moves in one of the X and Y directions, and continuously moves in the X direction, and the process is repeated to write on the entire surface of the workpiece W.

10. The exposure method according to claim 9, characterized in that: Each frame area is divided into a plurality of subfield areas arranged in a matrix manner; when writing on the frame area, the electron beam is positioned in each subfield area in the frame area through the main deflector (26), and then scanned to each writing position in the subfield area through the subdeflector (25), while the beam gate (23) intermittently prevents the electron beam B from irradiating the workpiece W; at this time, the electron beam B is shaped into a predetermined shape for each writing position by the shaping deflector (24), and the workpiece W is irradiated at each writing position with the electron beam B, thereby writing the desired pattern on each subfield area.

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