Wafer coating thickness indirect measurement using a dummy wafer and a coating fixture

Abstract

An accompanying piece and a film coating clamp for indirectly measuring the film thickness of a wafer belong to the technical field of film thickness probe measurement. The accompanying piece is composed of a square silicon substrate and an alloy mask closely adhered with a square through hole. The surface of the film coating clamp is a spherical cap, and multiple circular grooves are arranged circumferentially for placing the wafer. A rectangular groove is arranged between adjacent grooves for placing the accompanying piece, and semicircular grooves are arranged at the midpoint of both sides of the rectangular groove to adapt to the thickness of the mask. During film coating, the accompanying piece and the wafer are deposited with a thin film at the same time, and the film thickness of the wafer is indirectly calculated by measuring the height difference of the film step on the substrate of the accompanying piece. The length-width ratio and the through hole ratio of the accompanying piece can ensure the flatness of the film step, and the flatness and roughness of the substrate and the mask ensure close adhesion. The device avoids damage caused by direct contact with the wafer, solves the problems of large film thickness measurement error of high reflection material, shielding pollution, etc., and improves the measurement accuracy and reliability.

Description

Technical Field

[0001] This invention belongs to the field of film thickness probe measurement technology, specifically relating to a device capable of indirectly measuring the thickness of wafer coatings. Background Technology

[0002] Wafer anodes typically use metals or transparent conductive oxides as targets, which are then deposited onto the desired pixel locations using methods such as vacuum evaporation or sputtering to form a thin anode film. Holes transported from the anode recombine with electrons transported from the cathode in the light-emitting layer to form excitons. Since the excitons are not energized, they release light and heat to reach a stable state. Therefore, the thickness of the anode coating is a key technical indicator for evaluating wafers.

[0003] Currently, the thickness of anodic thin films is mainly measured by contact measurement, which uses a profilometer to measure the coating steps on the wafer. However, during the measurement process, the profilometer needs to be in direct contact with the sample surface, which may cause some damage or destruction to the wafer surface, affecting the yield of subsequent wafer processes. Furthermore, wafers are expensive, and frequent testing can easily lead to material waste and economic burden. Utility Model Content

[0004] This invention provides a wafer and a coating fixture for indirectly measuring the coating thickness of a wafer. The coating fixture is used to coat both the wafer and the wafer simultaneously, and then the wafer is measured, thus preventing damage to the wafer during the testing process.

[0005] A wafer and coating fixture for indirectly measuring wafer coating thickness, characterized only in that: the wafer consists of a substrate and a mask; the substrate is a square-cut silicon wafer; the mask is made of alloy material and cut into thin slices with the same outer dimensions as the substrate; a square through-hole is formed in the center of the mask; the mask is placed on the substrate and fits tightly against it; the coating fixture has a spherical cap surface, with at least two circular grooves of equal spacing and height arranged circumferentially on the surface of the coating fixture, centered on the center point of the top of the coating fixture; the diameter of the circular grooves is not less than the diameter of the wafer; in any two... A rectangular groove is provided between each adjacent circular groove. The number of rectangular grooves is at least one, and the distance from the center point of the rectangular groove to the center of the coating fixture is equal to the distance from the center of the circular groove to the center of the coating fixture. The size of the rectangular groove matches the outer size of the substrate. A semi-circular groove is opened at the midpoint of the opposite short side of the rectangular groove, and the depth of the semi-circular groove is the same as the thickness of the mask on the substrate. A lever is rotated and installed in the semi-circular groove. After the substrate is placed in the rectangular groove, the lever is rotated to block the mask of the substrate and limit the substrate.

[0006] Furthermore, the aspect ratio of the outer dimensions of the substrate and the mask is 11:8, and the aspect ratio of the square through hole is 31:26. This ratio can not only produce clean and flat metal thin film steps, but also meet the test requirements of sheet resistance and reflectivity of the deposited metal film.

[0007] Furthermore, the flatness of the substrate and the mask is 0.02 mm and the surface roughness is Ra 0.8 μm, so that the substrate and the mask can be tightly bonded.

[0008] The beneficial effects of this invention are as follows: The substrate and the wafer are placed on a coating fixture for simultaneous coating. After coating, the substrate is removed, and the mask on the substrate is taken off, resulting in thin film steps on the substrate. A profilometer is used to measure the height of the blank substrate and the substrate with the thin film steps. By calculating the height difference of the thin film steps, and considering that the substrate and the wafer are at the same height and angle, resulting in consistent coating thickness, the wafer coating thickness can be indirectly measured by measuring the height difference of the thin film steps on the substrate. This eliminates the need for direct measurement of the expensive wafer, avoiding wafer testing losses. The formation of thin film steps on the substrate, due to the rectangular grooves restricting the coating position, creates vertical thin film steps, leading to more accurate data when measured using a profilometer. The auxiliary film uses an alloy material for the mask and the substrate, which avoids the target material and the mask from dissolving or reacting during the thin film preparation process using physical vapor deposition equipment. This overcomes the problem of not being able to form thin film steps due to the use of photoresist or oil-based pen as a masking material. It also avoids a series of problems such as step contamination and unevenness caused by the residue left when using high-temperature tape as a masking material during removal, thus ensuring the accuracy of thin film step measurement. Attached Figure Description

[0009] Figure 1 This is a plan view of the coating fixture in Example 1.

[0010] Figure 2 This is a side view of the coating fixture in Example 1.

[0011] Figure 3 This is a schematic diagram of the liner structure in Example 1.

[0012] Figure 4 This is a schematic diagram of the wafer and the co-wafer being mounted in the coating fixture in Example 2.

[0013] Wherein: 1-coating fixture, 2-circular groove, 3-rectangular groove, 4-semi-circular groove, 5-accompanying piece, 6-substrate, 7-mask, 8-square through hole, 9-wafer, 10-paddle. Detailed Implementation

[0014] Example 1: A wafer and coating fixture for indirectly measuring wafer coating thickness, comprising a wafer 5 and a coating fixture 1. The wafer 5 consists of a substrate 6 and a mask 7. The substrate 6 is a silicon wafer cut into a square shape. The mask 7 is made of alloy material and cut into a thin sheet with the same outer dimensions as the substrate 6. A square through-hole 8 is opened in the center of the mask 7. The mask 7 is placed on the substrate 6 and is tightly attached to the substrate 6. The aspect ratio of the outer dimensions of the substrate 6 and the mask 7 is 11:8, and the aspect ratio of the square through-hole 8 is 31:26. This ratio can produce a clean and flat metal thin film step, and the deposited metal film layer can meet the test requirements of sheet resistance and reflectivity. The flatness of the substrate 6 and the mask 7 is 0.02 mm, and the surface roughness is Ra 0.8 μm, so that the substrate 6 and the mask 7 can be tightly attached. The surface of the coating fixture 1 is a spherical cap. With the center point of the top of the coating fixture 1 as the center, four circular grooves 2 are set circumferentially on the surface of the coating fixture 1 at equal intervals and heights. The diameter of the circular grooves 2 is not less than the diameter of the wafer 9. A rectangular groove 3 is set between any two adjacent circular grooves 2. The distance from the center point of the rectangular groove 3 to the center of the coating fixture 1 is equal to the distance from the center of the circular groove 2 to the center of the coating fixture 1. The size of the rectangular groove 3 matches the outer size of the substrate 5. A semi-circular groove 4 is opened at the midpoint of the opposite short side of the rectangular groove 3. The depth of the semi-circular groove 4 is the same as the thickness of the mask 7 on the substrate 5. A lever 10 is rotatably installed in the semi-circular groove 4. After the substrate 5 is placed in the rectangular groove 3, the lever 10 is rotated into the rectangular groove 3 to block the mask 7 of the substrate 5 and limit the substrate 5.

[0015] In use, the wafer 5 is placed in the rectangular groove 3 and positioned by the lever 10. The wafer 9 is placed in the circular groove 2. Both wafer 5 and wafer 9 are deposited simultaneously. After deposition, the wafer is removed. When removing or placing the wafer, the edge of the mask 7 on the wafer 5 is handled using the space of the semi-circular groove 4, thus avoiding contamination of the substrate 6. Then, the mask 7 on the wafer 5 is removed, forming thin film steps on the substrate 6. A profilometer is used to measure the height of the blank substrate 6 and the height of the substrate 6 with thin film steps. By calculating the height difference of the thin film steps, the deposition thickness of the wafer 9 can be indirectly measured.

[0016] Example 2: As described in Example 1, this example uses a substrate and coating fixture for indirectly measuring wafer coating thickness. The coating fixture in this example has two rectangular grooves 3 positioned opposite each other on the coating fixture 1, and two substrates 5 are simultaneously placed inside. After coating is completed, a step meter is used to measure the metal film steps on the two substrates. This allows for the determination of the coating thickness of adjacent wafers 9 for each substrate 5, or the average of the film thicknesses measured on the two substrates 5 can be calculated to obtain the average coating thickness of the wafer 9.

Claims

1. A wafer and coating fixture for indirectly measuring wafer coating thickness, characterized only in that: The auxiliary wafer consists of a substrate and a mask. The substrate is a square silicon wafer, and the mask is made of alloy material and cut into thin slices with the same outer dimensions as the substrate. A square through-hole is opened in the center of the mask, and the mask is placed on the substrate and fits tightly against the substrate. The surface of the coating fixture is a spherical cap. With the center point of the top of the coating fixture as the center, at least two circular grooves are set circumferentially on the surface of the coating fixture at equal intervals and heights. The diameter of the circular grooves is not less than the diameter of the wafer. A rectangular groove is set between any two adjacent circular grooves. The number of rectangular grooves is at least one, and the distance from the center point of the rectangular groove to the center of the coating fixture is the same as the distance from the center of the circular groove to the center of the coating fixture. The size of the rectangular groove matches the outer dimensions of the auxiliary wafer. A semi-circular groove is opened at the midpoint of the opposite short side of the rectangular groove, and the depth of the semi-circular groove is the same as the thickness of the mask on the auxiliary wafer. A lever is rotated and installed in the semi-circular groove. After the auxiliary wafer is placed in the rectangular groove, the lever is rotated into the rectangular groove, and the mask blocking the auxiliary wafer limits its position.

2. The wafer and coating fixture for indirectly measuring wafer coating thickness as described in claim 1, characterized in that... The aspect ratio of the outer dimensions of the substrate and mask is 11:8, and the aspect ratio of the square through-hole is 31:

26.

3. The wafer and coating fixture for indirectly measuring wafer coating thickness as described in claim 1, characterized in that... The flatness of the substrate and the mask is 0.02 mm, and the surface roughness is Ra 0.8 μm.

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