IBE processing method

Abstract

The IBE machining method comprises the steps that a bearing table 1 bears a wafer 2 to conduct positioning autorotation, then an etching baffle in a machining cavity is opened so that an ion source can bombard the wafer 2 on the bearing table 1, meanwhile, the bearing table 1 is controlled to adjust the deflection angle theta step by step, and through step-by-step adjustment of the deflection angle and combination of the progressively-increasing direction, the progressively-decreasing direction or the alternately-changing direction, the wafer 2 on the bearing table 1 can be bombarded; the dynamic optimization of the incident angle of the ion beam is realized, the etching concentric circle effect caused by a single angle in the traditional method is avoided, and the error of etching uniformity is greatly reduced; the machining time length is set according to the angle size difference, and the thickness uniformity is optimized; and clockwise and anticlockwise alternate rotation return is adopted, and the angle rotation of the wafer carrier at each time is less than or equal to 10 degrees, so that the displacement of the wafer 2 caused by accumulation of mechanical stress is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of plasma etching, and more specifically, to an IBE processing method. Background Art

[0002] In the manufacturing process of semiconductor devices and chips, etching process is the most frequently used and most common process. In the etching process of IC manufacturing, some materials on the chip will be partially or completely etched or removed. Among all etching processes, plasma etching and ion beam etching (IBE) are becoming more and more important, especially with the increase of chip integration, reduction of key dimensions, high selectivity and precise pattern transfer, which further highlights the advantages of plasma etching and ion beam etching.

[0003] At present, IBE etches at a constant angle during the etching process. Concentric circle etching rates are likely to occur during the etching process, resulting in a uniformity error of more than 5%, making it difficult to control product process stability.

[0004] In view of this, the present invention provides an IBE processing method with uniform etching and high etching yield. Summary of the invention

[0005] In view of this, in order to solve the above problems, the present invention proposes an IBE processing method, comprising the following steps: Step 1: Etching preparation, evacuate the processing chamber to Pa or less, and inert gas is introduced into the ion source. Step 2: Distributed angle etching, the carrier 1 carries the wafer 2 for positioning and rotation, then the etching baffle in the processing chamber is opened to allow the ion source to bombard the wafer 2 on the carrier 1, and at the same time the carrier 1 is controlled to adjust the deflection angle θ in steps, the deflection angle θ changes between at least three different predetermined angles, and the processing time after each change is at least 3 seconds, Step 3: After the etching is completed and the set etching time is reached, the baffle is closed, the carrier 1 drives the wafer 2 to return to 0° at multiple angles and the ion source is turned off.

[0006] Furthermore, the deflection angle θ is in the range of 60°≥θ≥35°.

[0007] Furthermore, the deflection angle θ is adjusted in steps of 5°-15°, and the angle adjustment directions of two adjacent steps include increasing, decreasing or alternating changes.

[0008] In some embodiments, in step 2, at least five different deflection angles are covered in a single processing process.

[0009] In some embodiments, in step 2, the deflection angle θ of the wafer 2 stage 1 is adjusted successively to: 55°, 40°, 45°, 50°, 55°, 60°, 55°, 50°, 45°, 40°, 35°, and the processing duration for each step is 3 - 5 seconds.

[0010] Furthermore, when the deflection angle θ is 55°, 50° or 60°, the processing duration is 5 seconds; when the rotation angle θ is 40°, 45° or 35°, the processing duration is 3 seconds, to prevent concentric circle etching and ensure uniform etching thickness.

[0011] In some embodiments, in step 1, specifically, for etching preparation, when the processing chamber reaches 5.0EX4 pa, one of argon, krypton or xenon is introduced into the ion source, and preferably argon.

[0012] In some embodiments, in step 3, the stage 1 returns to the initial angle in a multi - angle manner by alternating clockwise rotation and counter - clockwise rotation, and each rotation ≤ 10°, to avoid displacement of the wafer 2.

[0013] Advantages of the present invention: The present invention provides an IBE processing method. The stage 1 holds the wafer 2 for positioning and rotation, then the etching baffle in the processing chamber is opened so that the ion source bombards the wafer 2 on the stage 1. At the same time, the deflection angle θ of the stage 1 is controlled to be adjusted step by step. By adjusting the deflection angle step by step and combining increasing, decreasing or alternating directions, the dynamic optimization of the ion beam incident angle is realized, avoiding the etching concentric circle effect caused by a single angle in the traditional method, and greatly reducing the error of etching uniformity; the processing duration is set differently according to the angle size to optimize the thickness uniformity; the stage is rotated back to the initial position by alternating clockwise and counter - clockwise rotations, and each time the angle of the wafer stage 1 rotates ≤ 10°, reducing the displacement of the wafer 2 caused by the accumulation of mechanical stress. Description of the Drawings

[0014] Figure 1 It is the processing flow chart of the IBE processing method of the present invention.

[0015] Figure 2 It is the schematic diagram of the stage and wafer processing of the IBE processing method of the present invention.

[0016] Figure 3 It is the schematic diagram of the wafer detection points of the IBE processing method of the present invention.

[0017] Description of the Main Element Symbols Stage 1, Wafer 2, Test Point 3.

[0018] The following specific embodiments will further illustrate the present invention in conjunction with the above - mentioned drawings. Specific Embodiments Example 1:

[0019] As shown Figure 1 in the figure, it is the processing flow chart of the IBE processing method of the present invention; as shown Figure 2 in the figure, it is the schematic diagram of the processing of the stage 1 and the wafer 2 in the IBE processing method of the present invention.

[0020] The present invention provides an IBE processing method. Step 1: Etching preparation. The processing chamber is evacuated to below pa, and an inert gas is introduced into the ion source. Step 2: Angular distribution etching. The stage 1 holds the wafer 2 for positioning and rotation. Then, the etching baffle in the processing chamber is opened so that the ion source bombards the wafer 2 on the stage 1. At the same time, the stage 1 is controlled to stepwise adjust the deflection angle θ. The deflection angle θ is adjusted to 55°, 40°, 45°, 50°, 55°, 60°, 55°, 50°, 45°, 40°, 35° in sequence. When the deflection angle θ is 55°, 50° or 60°, the processing duration is 5 seconds; when the rotation angle θ is 40°, 45° or 35°, the processing duration is 3 seconds, to prevent concentric circle etching and ensure uniform etching thickness. Step 3: Complete etching. When the etching set time is reached, the baffle is closed, and the stage 1 drives the wafer 2 to return to 0° at multiple angles and the ion source is closed. Among them, each rotation during the multi-angle return is ≤10°.

[0021] For the multi-angle etched wafer processed in the above manner, data testing is carried out. Testing method: as shown Figure 3 in the figure, 10 test points are evenly spaced along the diameter of the wafer and tested. The formula for etching uniformity is: etching uniformity = (1 - S / th) * 100%, where S is the difference between the maximum and minimum thicknesses measured at the test points on the wafer, and th is the average value of all measurement points / 2.

[0022] The test data of the multi-angle etched wafer and the etched wafer processed by the traditional constant angle are shown in Table 1: Table 1:

[0023] It can be seen from Table 1 that the uniformity of the multi-angle etched wafer is improved by about 4% compared with the etched wafer processed by the constant angle, effectively improving the etching uniformity.

[0024] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. An IBE processing method, characterized in that, including the following steps, Step 1: Etching preparation. Evacuate the processing chamber to below Pa and introduce an inert gas into the ion source. Step 2: Angular distributed etching. The stage (1) holds the wafer (2) for positioning and rotation. Then, the etching baffle in the processing chamber is opened so that the ion source bombards the wafer (2) on the stage (1). At the same time, the stage (1) is controlled to stepwise adjust the deflection angle θ, and the deflection angle θ varies among at least three different predetermined angles. After each change, the processing duration is at least 3 seconds. Step 3: Finish etching. When the etching set time is reached, the baffle is closed. The stage (1) drives the wafer (2) to return to 0° at multiple angles and the ion source is turned off. The range of the deflection angle θ is 60° ≥ θ ≥ 35°, the adjustment step of the deflection angle θ is 5° - 15°, and the angular adjustment directions of adjacent two steps include increasing, decreasing, or alternating changes.

2. The IBE processing method according to claim 1, characterized in that: In Step 2, at least 5 different deflection angles are covered during a single processing.

3. The IBE processing method according to claim 2, wherein: In Step 2, the deflection angle θ of the wafer (2) stage (1) is sequentially adjusted to: 55°, 40°, 45°, 50°, 55°, 60°, 55°, 50°, 45°, 40°, 35°, and the processing duration for each step is 3 - 5 seconds.

4. The IBE processing method according to claim 5, characterized in that: When the deflection angle θ is 55°, 50°, or 60°, the processing duration is 5 seconds; when the rotation angle θ is 40°, 45°, or 35°, the processing duration is 3 seconds, to prevent concentric circle etching and ensure uniform etching thickness.

5. The IBE processing method according to claim 1, wherein: In step 1, specifically, for etching preparation, when the processing chamber reaches pa, one of argon, krypton, or xenon is introduced into the ion source.

6. The IBE processing method according to claim 1, characterized in that: In Step 3, the stage (1) returns to the initial angle in a multi-angle manner by alternately rotating clockwise and counterclockwise. Each time the angle of the wafer stage (1) rotates ≤ 10°, to avoid displacement of the wafer (2).

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