Correction structure for improving thickness uniformity of ZnS film grown by magnetron sputtering

Abstract

The utility model relates to a correction structure for improving the thickness uniformity of a ZnS film grown by magnetron sputtering. The correction structure comprises an anode cap gasket, a bracket, a molybdenum sheet and a balancing weight, the anode cap gasket is a planar circular ring, the outer ring diameter is consistent with the anode cap diameter, the anode cap gasket can cover the anode cap, and the inner ring does not shield the target material; the molybdenum sheet is located above the circular ring of the anode cap gasket, the area of the molybdenum sheet accounts for 2.5%-7% of the area of the target material, and a small hole is formed in the intersection point of the center of the long edge of the molybdenum sheet and 1 / 4 of the short edge of the molybdenum sheet and serves as a through hole of a longitudinally-arranged support connecting screw; the two balancing weights are symmetrically welded to the anode cap gasket, one balancing weight is used for adjusting balance of the anode cap gasket, a through hole is formed in the center of the horizontal plane of the other balancing weight and serves as a support through hole, and a screw hole is machined in the center of the face adjacent to the horizontal plane. According to the utility model, the thickness non-uniformity performance of the ZnS passive film can be superior to + / -2.5%.

Description

Technical Field

[0001] This invention belongs to the field of infrared focal plane array detection, specifically relating to a correction structure for improving the thickness uniformity of ZnS thin films grown by magnetron sputtering. Background Technology

[0002] Currently, Hg is used as a core material in third-generation detectors. 1-x Cd x Te remains the highest-performing mainstream detector material, enabling detection from short to long and even very long wavelengths by adjusting the Cd composition (x). However, MCTs are narrow-bandgap semiconductors, and dark current is a key factor limiting their performance. High-quality passivation films can reduce the impact of surface and interface states on device performance.

[0003] ZnS, as a high-dielectric thin film, effectively protects chips from external electrical signals, moisture, and other influences. In the CdTe / ZnS double-layer passivation process, the ZnS film effectively reduces the impact of slow interface states on the chip. This is mainly reflected in the fact that the ZnS film in the double passivation film is a high-dielectric layer, which can isolate the influence of external charge carriers to a certain extent. When the chip is under operating voltage, it can effectively capture and release internally generated charge carriers, reducing band tail shift. Simultaneously, for chips with small pixel pitch, ZnS can also isolate signal interference between pixels and the diffusion of metal atoms to a certain extent.

[0004] The uniformity of ZnS thickness affects subsequent processes such as photolithography, etching for opening holes, ion implantation, and metallization, ultimately leading to a significant impact on device performance. Poor ZnS thickness uniformity not only affects the ZnS film itself, causing uneven stress and making it prone to film bursting due to external factors, but also increases the difficulty of subsequent processes.

[0005] The deposition of ZnS passivation films in MCT chips primarily relies on radio frequency magnetron sputtering. Due to the inner and outer ring-shaped distribution of the magnetic field in the equipment, the magnetic field lines on the ZnS target surface are directed from the center to the edge. This causes electrons to be confined in the middle region of the magnetic field lines, resulting in a helical motion. The probability of collisions with Ar+ ions also exhibits a certain degree of cosine distribution with the magnetic field distribution. Ultimately, etching channels appear on the target surface, and the sputtering rates of atoms or atomic clusters on the target surface are inconsistent. This leads to more pronounced non-uniformity in the film thickness deposited on the substrate. Furthermore, the eccentricity angle between the target and the substrate is 30º~60º, resulting in a thickness difference of more than 5% between the center and edge of the sample disk. Therefore, the passivation process using ZnS thin film technology cannot meet the requirements of chip manufacturing processes.

[0006] Currently, the chip size of infrared detectors is developing towards larger sizes, such as 2k*2k and 4k*4k. The thickness uniformity of ZnS thin films grown by magnetron sputtering is increasingly unable to meet the process requirements. Utility Model Content

[0007] To address the issue that the uniformity of ZnS passivation film thickness grown by magnetron sputtering cannot meet current process requirements, this invention provides a correction structure for improving the uniformity of ZnS film thickness grown by magnetron sputtering. This correction structure effectively improves the uniformity of ZnS passivation film thickness without affecting the glow discharge and plasma characteristics of magnetron sputtering. The correction structure is simple to manufacture and suitable for use in equipment for preparing ZnS passivation films by magnetron sputtering. It mainly consists of five parts: an anode cover gasket, a support, a molybdenum sheet, a counterweight, and screws.

[0008] Furthermore, the anode cover gasket is a planar circular ring with a thickness of 0.5mm to 2.5mm and a width of 15mm to 30mm. The outer ring diameter is consistent with the diameter of the anode cover and can cover the anode cover, while the inner ring cannot block the target material.

[0009] Furthermore, the bracket is used to adjust the height of the molybdenum sheet on the calibration plate, ensuring that the molybdenum sheet is positioned between the cathode dark area and the target material without affecting glow discharge. The ratio of the molybdenum sheet height to the target distance is between 3 / 11 and 6 / 11. In this invention, the bracket consists of two stainless steel rods welded together. The thicker stainless steel rod, with dimensions of Φ3mm to Φ5mm, is connected to the anode cover washer. One end of the rod is bent at 90°, and the bracket is secured by screws. The other stainless steel rod, with dimensions of Φ1.5mm to Φ2.5mm, serves as the carrier for the molybdenum sheet and has a screw hole in the middle for connecting and fixing the molybdenum sheet to the bracket via screws.

[0010] Furthermore, the molybdenum sheet is rectangular in shape. In practical applications, the shape can be designed according to the non-uniformity of the grown film layer, and the area accounts for about 2.5% to 7% of the target material area. Since the molybdenum sheet in this invention is mainly used in magnetron sputtering equipment, where the sputtering ion energy is high, if the molybdenum sheet is too thin, it will easily deform. In order to increase the life of the correction structure, the molybdenum sheet in this invention is designed to be relatively thick, with a thickness of 1mm to 3mm. A small hole is drilled at the intersection of the center of the long side and 1 / 4 of the short side of the molybdenum sheet, which is used as a through hole for connecting screws to the longitudinally arranged support.

[0011] Furthermore, the correction structure is applicable to all MCT chips or other chip processes that require ZnS thin films as passivation films. The target material is a relatively uniform ZnS target material grown by CVD, with a size in the range of 4 to 12 inches.

[0012] Furthermore, the material of the correction structure is matched to the stainless steel material of the anode cover of the magnetron sputtering equipment, or molybdenum with relatively good conductivity can be selected.

[0013] Furthermore, two counterweights are symmetrically welded to the anode cover gasket. One of them is used to adjust the balance of the anode cover gasket, and the other has a through hole in the center of its horizontal plane, with a size of Φ3mm~Φ5mm, which is used as a support through hole. A screw hole is machined in the center of the side adjacent to the horizontal plane. The support is fixed by tightening the screw, and the height of the support can be adjusted by loosening the screw.

[0014] Furthermore, there are two screws, one for fixing the bracket and the other for fixing the molybdenum sheet to the bracket, both with dimensions of Φ1mm~Φ4.5mm.

[0015] The beneficial effects of this utility model are:

[0016] This invention provides a correction structure to address the problem that the thickness uniformity of ZnS passivation films grown by magnetron sputtering does not meet current process requirements. This correction structure effectively improves the thickness uniformity of the ZnS passivation film without affecting the glow discharge and plasma characteristics of magnetron sputtering. The fabrication method of this correction structure is simple and applicable to equipment used for preparing ZnS passivation films by magnetron sputtering. Testing shows that this invention can achieve a ZnS passivation film thickness non-uniformity better than ±2.5%. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall correction structure of this utility model.

[0018] Figure 2 This is a schematic diagram of the structure of the molybdenum sheet and the support.

[0019] Figure 3 This is a structural diagram of the bracket and screws.

[0020] The components include: 1. Anode cover gasket; 2. Bracket; 3. Molybdenum sheet; 4. Counterweight; 5. Screw. Detailed Implementation

[0021] To make the structure, purpose and advantages of this utility model clearer, the following detailed description of this utility model is provided in conjunction with the accompanying drawings.

[0022] like Figure 1-3 As shown, the calibration structure includes an anode cover washer 1, a bracket 2, a molybdenum sheet 3, a counterweight 4, and a screw 5. The anode cover washer 1 serves a supporting function in this invention. Its material matches the stainless steel material used in magnetron sputtering anode covers, but molybdenum, which has relatively good conductivity, can also be used. The washer is a flat circular ring with a thickness of 0.5mm to 2.5mm and a width of 15mm to 30mm. The outer diameter is the same as the diameter of the anode cover, covering it, while the inner ring does not obstruct the target material.

[0023] Two counterweights 4 are symmetrically welded onto the anode cover gasket 1. One of them is simply welded onto the anode cover gasket 1 without any machining and is used to adjust the balance of the anode cover gasket 1. The other counterweight has a through hole of Φ3mm~Φ5mm at the center of its horizontal surface, which serves as the through hole for the support 2. A screw hole is machined at the center of the surface adjacent to the horizontal surface. The support 2 is fixed by tightening the screw 5 in the screw hole, and the height of the support 2 can be adjusted by loosening the screw 5. The ultimate goal is to ensure that the molybdenum sheet 3, which serves as the correction plate, is located in the dark area of ​​the magnetron sputtering discharge zone, without affecting the plasma discharge characteristics.

[0024] Cut the molybdenum sheet 3 into 50*60cm pieces using scissors. 2 The rectangular shape can be rationally designed according to the non-uniformity of the grown film in practical applications, and its area accounts for about 2.5% to 7% of the target area. Since the molybdenum sheet 3 in this utility model is mainly used in magnetron sputtering equipment with high electron energy of 300eV to 500eV, if the molybdenum sheet is too thin, it will easily deform. In order to increase the life of the correction structure, the molybdenum sheet 3 in this utility model is designed to be relatively thick, with a thickness of 1mm to 3mm. A small hole is drilled at the intersection of the center of the long side and 1 / 4 of the short side of the molybdenum sheet 3. The molybdenum sheet 3 is fixed to the bracket 2 with screws 5, and the edge of the molybdenum sheet 3 is kept parallel to the bracket 2.

[0025] like Figure 3 As shown, the bracket 2 is made of two stainless steel rods welded together. The thicker stainless steel rod is connected to the anode cover washer 1, with a size of Φ3mm~Φ5mm. One end of the rod is bent at 90° and screw 5 is tightened to fix the bracket 2. The other stainless steel rod connected to the bent end serves as the carrier of the molybdenum sheet 3, with a size of Φ1.5mm~Φ2.5mm. There is a screw hole in the middle position, and screw 5 is used to fix the molybdenum sheet 3 to the bracket 2.

[0026] A ZnS passivation film of approximately 2500 Å was grown on an 8-inch Si wafer. After testing, its thickness non-uniformity was better than ±2%, which meets the current process requirements.

Claims

1. A correction structure for improving the thickness uniformity of ZnS thin films grown by magnetron sputtering, characterized in that, The correction structure includes an anode cover gasket (1), a bracket (2), a molybdenum sheet (3), and a counterweight (4); The anode cover gasket (1) is a planar circular ring. Its outer diameter is consistent with the diameter of the anode cover and can cover the anode cover, while its inner ring does not block the target material. The molybdenum sheet (3) is located above the ring of the anode cover gasket (1), and its area accounts for 2.5% to 7% of the target material area. A small hole is punched on the molybdenum sheet (3) to serve as a through hole for connecting screws to the longitudinally arranged bracket (2). The counterweight (4) consists of two pieces, which are symmetrically welded to the anode cover gasket (1). One piece is used to adjust the balance of the anode cover gasket (1), and the other piece has a through hole in the center of the horizontal plane, which is used as a through hole for the bracket (2). A screw hole is machined in the center of the side adjacent to the horizontal plane. The bracket (2) is fixed by tightening the screw in the screw hole, and the height of the bracket (2) can be adjusted by loosening the screw.

2. The correction structure according to claim 1, characterized in that: The bracket (2) is made of two rods welded together. The thicker rod is connected to the anode cover gasket (1), and one end of it is bent at 90°. The bracket is fixed by the compression of the screw. The other rod connected to the bent end serves as the carrier of the molybdenum sheet (3). There is a screw hole in the middle position. The screw hole is used as a through hole for the molybdenum sheet (3) and the bracket (2) to be fixed by screws.

3. The correction structure according to claim 1, characterized in that: The small hole on the molybdenum sheet (3) is located at the intersection of the center of the long side and 1 / 4 of the short side of the molybdenum sheet (3).

4. The correction structure according to claim 1, characterized in that: The bracket (2) is made of stainless steel rod.

5. The correction structure according to claim 4, characterized in that: The thicker support (2) has a diameter of Φ3mm to Φ5mm, and the other has a diameter of Φ1.5mm to Φ2.5mm.

6. The correction structure according to claim 1, characterized in that: The height of the molybdenum sheet (3) is adjusted by the bracket (2) so that the molybdenum sheet (3) is located between the cathode dark area and the target material without affecting the glow discharge.

7. The correction structure according to claim 6, characterized in that: The ratio of the height of the molybdenum sheet (3) to the distance from the target base is between 3:11 and 6:

11.

8. The correction structure according to any one of claims 1-7, characterized in that: The anode cover gasket (1) and the counterweight (4) are made of stainless steel or molybdenum.

9. The correction structure according to any one of claims 1-7, characterized in that: The thickness of the anode cover gasket (1) is 0.5mm to 2.5mm and the width is 15mm to 30mm.

10. The correction structure according to any one of claims 1-7, characterized in that: The thickness of the molybdenum sheet (3) is 1 mm to 3 mm.

Images