Method for segmentally measuring wet etching rate of hemisphere of crystal

Abstract

The invention discloses a method for segmentally measuring the wet etching rate of a crystal hemisphere. The method comprises the following steps: firstly, dividing the crystal hemisphere into a low-rate region, a medium-rate region and a high-rate region in a direction from an equator to a north pole; determining the etching time of the high-rate region, the medium-rate region, the low-rate region and the crystal hemisphere; the method comprises the following steps: setting four crystal hemispheres with the same size, respectively determining the etching time of a high-rate region, a medium-rate region, a low-rate region and the crystal hemispheres, and carrying out wet etching along the respective divided corresponding regions to obtain the ratio of the respective radial etching distance to the etching time; and finally, synthesizing the etching rate data of the high-rate region, the medium-rate region and the low-rate region by referring to the etching rate of the hemisphere of the crystal to obtain the whole crystal face etching rate of the crystal. According to the method, the crystal hemisphere is divided into the high etching rate area, the middle etching rate area and the low etching rate area, and different etching time is determined according to different areas, namely, the rate of each etching area is measured in a segmented manner so as to accurately obtain the whole crystal face etching rate of the crystal.

Description

Technical Field

[0001] The invention belongs to the field of measuring crystal hemisphere wet etching rate, and in particular relates to a method for measuring the crystal hemisphere wet etching rate in sections. Background Art

[0002] The full-crystal surface etching rate plays the role of a database in the wet etching research of crystals. Accurately obtaining the full-crystal surface etching rate of crystals is the key to studying the wet etching mechanism and modeling process models.

[0003] The measurement of the full crystal surface etching rate mainly includes the crystal plane interpolation method and the hemispherical specimen measurement method. Among them, the crystal plane interpolation method selects a limited number of crystal planes in batches for wet etching experiments. The rationality of the crystal plane selection and the correct application of the interpolation method affect the accuracy of the full crystal surface etching rate, and the experimental cycle is long and the cost is high. The existing crystal hemispherical specimen measurement method has the ability to measure the etching rate of all crystal planes at once. It obtains the etching rate of the crystal plane by calculating the ratio of the radial etching distance of the crystal plane to the etching time. The schematic diagram of the etching rate calculation is shown in the figure. Figure 1 As shown in the figure, the surface coordinates before and after etching are obtained by a three-coordinate measuring instrument, so as to calculate the radial etching distance during etching. The ratio of the radial etching distance to the etching time is the etching rate of the crystal plane at this position. Therefore, the hemispherical specimen measurement method has a great advantage in measuring the etching rate of the entire crystal surface.

[0004] However, due to the extremely low etching rate at the equatorial edge of crystal materials such as quartz and sapphire, when the hemispherical specimen measurement method is used for etching experiments, a short etching time can easily lead to shallow etching at the equatorial edge, resulting in a large measurement error for low etching rates; a long etching time can easily lead to over-etching at the top of the hemisphere, resulting in a large measurement error for high etching rates. That is, the full crystal surface etching rate obtained by the existing hemispherical specimen measurement method usually needs to be repeatedly calibrated and corrected, which seriously affects the development and application of crystal wet etching.

[0005] Based on this, a new method for measuring the crystal hemispherical wet etching rate is studied, which can effectively solve the etching drawbacks caused by the existing etching time, so as to accurately obtain the full crystal surface etching rate of the crystal. Summary of the invention

[0006] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for segmented measurement of the hemispherical wet etching rate of a crystal, which can effectively solve the etching drawbacks caused by the existing etching time, so as to accurately obtain the full crystal surface etching rate of the crystal.

[0007] Technical solution: The method for measuring the crystal hemisphere wet etching rate in sections of the present invention comprises the following steps:

[0008] (1) Divide the crystal hemisphere with a latitude range of 0°≤β≤90° into a low-rate region, a medium-rate region and a high-rate region in the direction from the equator to the North Pole; wherein the latitude range of the low-rate region is 0°≤β<10°, the latitude range of the medium-rate region is 10°≤β<30°, and the latitude range of the high-rate region is 30°≤β≤90°;

[0009] (2) Determine the etching times of the high-rate region, medium-rate region, low-rate region, and crystal hemisphere, which are T1, T2, T3, and T4, respectively; determine that the etching rate corresponding to the crystal plane (0001) in the high-rate region is v1, and the etching rate corresponding to the crystal plane (1-101) or (-2111) in the medium-rate region is v2, and T1:T2=v2 1 / 2 :v1 1 / 2 , T3 is (2-3) times T2, T4 = T2;

[0010] (3) setting four crystal hemispheres of the same size, and setting the etching time of the high rate region, the medium rate region, the low rate region and the crystal hemisphere respectively, performing wet etching along the corresponding regions, and obtaining the ratio of the radial etching distance to the etching time, which is the etching rate of the corresponding coordinate point;

[0011] (4) Referring to the etching rate of the crystal hemisphere corresponding to the etching time T4, the etching rate data of the high rate area, medium rate area, and low rate area corresponding to the etching times T1, T2, and T3 are synthesized to obtain the full crystal surface etching rate of the crystal.

[0012] The present invention divides the crystal hemisphere into high, medium and low etching rate regions and determines different etching times according to different regions, that is, the etching rate of each etching region is measured in sections to accurately obtain the full crystal surface etching rate of the crystal.

[0013] Furthermore, in step (3) of the measurement method, when wet etching is performed, three-dimensional coordinate measurement of coordinate points is performed at intervals of 1-2° along the longitude direction of 0°≤α≤360° and the latitude direction of 0°≤β≤90°.

[0014] Furthermore, the clamping device used to place four crystal hemispheres of the same size in the measuring method includes a chassis, and the chassis is provided with a limit assembly and a fixing assembly at the positions corresponding to the placement of the crystal hemispheres respectively. The limit assembly includes a fixing pin arranged on the upper end surface of the chassis and a movable positioning pin assembly arranged on the chassis, and a slide groove cooperating with the movable positioning pin assembly is opened on the chassis.

[0015] Furthermore, the movable positioning pin assembly used in the crystal hemisphere clamping device includes a slider matched with the slide groove and a positioning pin arranged on the slider, and the crystal hemisphere is placed and limited by the positioning pin and the fixing pin.

[0016] Furthermore, the fixing assembly used in the crystal hemisphere clamping device includes a slider and a baffle disposed at one end of the slider, and a slide groove matching the slider is provided on the chassis.

[0017] Furthermore, the bottom end of the crystal hemisphere of the present invention is provided with a groove which matches with the positioning pin and the fixing pin.

[0018] Beneficial effects: Compared with the prior art, the significant advantages of the present invention are: the method of segmented measurement of the crystal hemisphere wet etching rate realizes an effective wet etching experiment on the crystal hemisphere, avoids shallow etching and over-etching of the hemisphere, and thus can obtain an effective full-crystal surface etching rate. In addition, a corresponding crystal hemisphere clamping device is designed, and the designed circular chassis has the same crystal hemisphere limiting assembly and fixing assembly, which can meet the segmented measurement requirements of the crystal hemisphere etching rate and ensure a high utilization rate of the experimental device; the designed movable positioning pin assembly can meet the positioning of crystal hemispheres of different radii, and the auxiliary fixing assembly further strengthens the stability of the hemisphere clamping; the entire device has a simple manufacturing process and low cost, is suitable for mass production and popularization, and also ensures the smooth implementation of the segmented measurement method. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of etching rate measurement using an existing hemispherical specimen measurement method;

[0020] Figure 2 It is a schematic diagram of measuring the crystal hemisphere etching rate in sections according to the present invention;

[0021] Figure 3 A crystal hemisphere clamping device that is compatible with the segmented measurement method of the present invention;

[0022] Figure 4 The etching rate curve of quartz in the <-1100> crystal direction region obtained based on the segmented measurement method of the present invention and the existing hemispherical specimen measurement method;

[0023] Figure 5 The etching rate curve of sapphire in the <11-20> crystal orientation region obtained based on the segmented measurement method of the present invention and the existing hemispherical specimen measurement method;

[0024] Figure 6Comparison of simulation and experiment on the groove etched structure (width of 23 μm) in the <11-20> crystal orientation region on the sapphire C(0001) surface wafer after etching for 4 hours: (a) experimental results; (b) simulation results based on the segmented measurement method; (c) simulation results based on the existing hemispherical specimen measurement method. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0026] like Figure 2 As shown, the method for measuring the crystal hemisphere wet etching rate in segments of the present invention comprises the following steps:

[0027] (1) Divide the crystal hemisphere with a latitude range of 0°≤β≤90° into a low-rate region, a medium-rate region and a high-rate region in the direction from the equator to the North Pole; wherein the latitude range of the low-rate region is 0°≤β<10°, the latitude range of the medium-rate region is 10°≤β<30°, and the latitude range of the high-rate region is 30°≤β≤90°;

[0028] (2) Determine the etching times of the high-rate region, medium-rate region, low-rate region, and crystal hemisphere, which are T1, T2, T3, and T4, respectively; determine the crystal plane (0001) located in the high-rate region and the crystal plane (1-101) or (-2111) located in the medium-rate region, whose etching rates are v1 and v2, respectively; where T1:T2=v2 1 / 2 :v1 1 / 2 , T3 is (2-3) times T2, T4 = T2; T2 can be obtained from the relevant known literature or actual experimental experience of the existing hemispherical specimen measurement method, and v2 and v1 are both obtained based on the etching time T2 using the corresponding wafer experiment;

[0029] (3) setting four crystal hemispheres of the same size, and setting the etching time of the high rate region, the medium rate region, the low rate region and the crystal hemisphere respectively, performing wet etching along the corresponding regions, and obtaining the ratio of the radial etching distance to the etching time, which is the etching rate of the corresponding coordinate point;

[0030] (4) Referring to the etching rate of the crystal hemisphere corresponding to the etching time T4, the etching rate data of the high rate area, medium rate area, and low rate area corresponding to the etching times T1, T2, and T3 are synthesized to obtain the full crystal surface etching rate of the crystal.

[0031] Based on the method for measuring the wet etching rate of a crystal hemisphere in sections of the present invention, a corresponding clamping device for placing four crystal hemispheres is provided, and the clamping device includes a circular chassis 1 and a lifting rod 2 arranged at the center of the circular chassis 1. The circular chassis 1 is provided with four groups of limiting components and fixed fixing components for limiting the placed crystal hemispheres, such as Figure 3 As shown. The limiting assembly includes a fixed pin 3 provided on the upper end surface of the chassis 1 and a movable positioning pin assembly provided on the chassis 1. The movable positioning pin assembly includes a slider 5 provided on the chassis 1. Correspondingly, a groove 4 matching the slider is provided on the chassis 1. A positioning pin 6 is provided on the slider 5. The positioning pin 6 and the fixing pin 3 cooperate to place and limit the crystal hemisphere. The fixing assembly also includes a slider 5 provided on the chassis 1 and a baffle 7 provided on the slider 5. Similarly, a groove 4 matching the slider 5 is provided on the chassis 1. The slider 5 and the baffle 7 of the fixing assembly are used to support the crystal hemisphere after the placement and limitation, thereby further improving its stability.

[0032] That is, the crystal hemisphere clamping device of the present invention has 4 groups of identical limiting components and fixing components, and can carry out wet etching experiments on 4 crystal hemispheres at the same time. Among them, 3 groups of limiting components and fixing components are used for measuring 3 spherical ring surfaces, corresponding to the high, medium and low areas of etching rate, respectively, and the etching time of the 3 hemispheres is set. Through etching experiments and measurements on the 3 spherical ring surfaces, a complete full-crystal surface etching rate is obtained in combination. The last crystal hemisphere is used for etching rate measurement of the existing hemisphere specimen measurement method. The full-crystal surface etching rate obtained by the combination is verified by observing the changes in the etching rate at the connection of the 3 spherical ring surfaces. The entire experimental device is made of high temperature and corrosion resistant polytetrafluoroethylene material.

[0033] Example 1

[0034] This embodiment 1 is based on the etching rate measurement of quartz (SiO2) under experimental conditions (HF:NH4F=3:2, 75°C), and specifically includes the following steps:

[0035] (1) Four quartz hemispheres of the same size (radius of 20 mm) are obtained (in order to facilitate the measurement of the coordinates of the equatorial edge of the quartz hemisphere, the latitude range of the quartz hemisphere is -10°≤β≤90°), marked as No. 1, No. 2, No. 3 and No. 4, respectively. Among them, the quartz hemispheres No. 1, No. 2 and No. 3 are divided into a high-rate region (30°≤β≤90°), a medium-rate region (10°≤β<30°) and a low-rate region (0°≤β<10°), respectively, and then cleaned and dried together.

[0036] (2) Use a three-dimensional coordinate measuring instrument to measure the surface coordinates of quartz hemispheres No. 1, 2, 3, and 4 in sequence, and perform three-dimensional coordinate measurement of coordinate points every 1°.

[0037] (3) Install the four quartz hemispheres into the experimental device in turn, place them in the solution pool (HF: NH4F = 3:2), and set the etching temperature required for the experiment to 75°C.

[0038] (4) Set the etching time of quartz hemispheres 1, 2, 3, and 4. First, T2 = 2h, the rate v1 of the crystal plane (0001) = 1.09μm / min, the rate v2 of the crystal plane (-2111) = 0.12μm / min, according to T1:T2 = v2 1 / 2 :v1 1 / 2 Calculation shows that T1≈1h, T3=3T2=6h, T4=T2=2h.

[0039] (5) After etching for T1 = 1 h, take out quartz hemisphere No. 1.

[0040] (6) After etching for T2 = 2 h, take out quartz hemispheres No. 2 and No. 4.

[0041] (7) After etching for T3 = 6 hours, take out quartz hemisphere No. 3.

[0042] (8) After etching, clean and dry the quartz hemispheres No. 1, 2, 3 and 4, and continue to use a three-coordinate measuring instrument to measure the surface coordinates of the quartz hemispheres No. 1, 2, 3 and 4 in sequence, using the same method as step (2).

[0043] (9) Based on the coordinate data measured before and after etching, the etching rate of the corresponding coordinate point is obtained by the ratio of the radial etching distance to the etching time.

[0044] (10) The full crystal surface etching rate of the synthesized quartz is calculated based on the etching rate data of quartz hemispheres No. 1, 2, and 3, and with reference to the etching rate data of quartz hemisphere No. 4.

[0045] Comparative Example 1

[0046] The existing hemisphere specimen measurement method is used to etch the quartz hemisphere for 2 hours, namely, the etching of quartz hemisphere No. 4.

[0047] The etching rate curves in the <-1100> crystal orientation region obtained by the two measurement methods of Example 1 and Comparative Example 1 are compared, and the results obtained are as follows: Figure 4 As shown. Figure 4 It can be seen that after applying the existing hemispherical specimen measurement method to conduct a wet etching experiment on a quartz hemisphere, shallow etching occurs in the low-rate area, resulting in a large rate measurement error, and over-etching occurs in the high-rate area, resulting in a large rate measurement error; while the etching rate curve obtained by the segmented measurement method proposed in the present invention has a reasonable distribution, avoiding shallow etching and over-etching phenomena.

[0048] Example 2

[0049] This embodiment 2 is based on the sapphire (Al2O3) etching rate measurement under the experimental conditions (H2SO4:H3PO4=3:1, 230°C), and specifically includes the following steps:

[0050] (1) Four sapphire hemispheres of the same size (radius 24 mm) were obtained (in order to facilitate the measurement of the coordinates of the equatorial edge of the sapphire hemisphere, the latitude range of the sapphire hemisphere is -10°≤β≤90°), marked as No. 1, No. 2, No. 3 and No. 4, respectively. The sapphire hemispheres No. 1, No. 2 and No. 3 were divided into a high-rate region (30°≤β≤90°), a medium-rate region (10°≤β<30°) and a low-rate region (0°≤β<10°), and then cleaned and dried together.

[0051] (2) Use a three-dimensional coordinate measuring instrument to measure the surface coordinates of sapphire hemispheres No. 1, 2, 3, and 4 in sequence, and perform three-dimensional coordinate measurement of coordinate points every 2°.

[0052] (3) Install four sapphire hemispheres into the experimental device in turn, place them in a solution pool (H2SO4:H3PO4=3:1), and set the etching temperature required for the experiment to 230°C.

[0053] (4) Set the etching time of sapphire hemispheres No. 1, 2, 3 and 4. First, T2 = 20h, the rate v1 of the crystal plane (0001) = 1.58μm / h, the rate v2 of the crystal plane (1-101) = 0.12μm / h, according to T1:T2 = v2 1 / 2 :v1 1 / 2 Calculation shows that T1≈6h, T3=2T2=40h, T4=T2=20h.

[0054] (5) After etching for T1 = 6 h, take out sapphire hemisphere No. 1.

[0055] (6) After etching time T2 = 20 h, take out sapphire hemispheres No. 2 and No. 4.

[0056] (7) After etching for T3 = 40 h, take out sapphire hemisphere No. 3.

[0057] (8) After etching, clean and dry the sapphire hemispheres No. 1, 2, 3 and 4, and continue to use a three-coordinate measuring instrument to measure the surface coordinates of the sapphire hemispheres No. 1, 2, 3 and 4 in sequence, using the same method as step (2).

[0058] (9) Based on the coordinate data measured before and after etching, the etching rate of the corresponding coordinate point is obtained by the ratio of the radial etching distance to the etching time.

[0059] (10) The full crystal surface etching rate of sapphire is synthesized based on the etching rate data of sapphire hemispheres No. 1, 2, and 3, and with reference to the etching rate data of sapphire hemisphere No. 4.

[0060] Comparative Example 2

[0061] The existing hemisphere specimen measurement method is used to etch the sapphire hemisphere for 20 hours, namely, etching of sapphire hemisphere No. 4.

[0062] The etching rate curves of sapphire in the <11-20> crystal orientation region obtained by the two measurement methods of Example 2 and Comparative Example 2 are compared, and the results obtained are as follows: Figure 5 As shown. Figure 5 It can be seen that after applying the existing hemispherical specimen measurement method to conduct a wet etching experiment on a sapphire hemisphere, shallow etching occurs in the low-rate area, resulting in a large rate measurement error, and over-etching occurs in the high-rate area, resulting in a large rate measurement error; while the etching rate curve obtained by the segmented measurement method proposed in the present invention has a reasonable distribution, avoiding shallow etching and over-etching phenomena.

[0063] In order to further demonstrate the significant advantages of the segmented measurement method proposed in the present invention, the Wulff-Jaccodine method based on the etching rate curve to simulate the etching structure is used to compare the simulation results with the experimental results. Figure 6 It can be seen that compared with the existing hemispherical specimen measurement method, the sapphire groove structure simulation results obtained based on the segmented measurement method are closer to the experimental results, which shows that the segmented measurement method proposed in the present invention can avoid shallow etching and over-etching of the hemisphere, making the obtained etching rate more accurate.

Claims

1. A method for measuring the crystal hemisphere wet etching rate in segments, characterized in that: The steps include: (1) Divide the crystal hemisphere with a latitude range of 0°≤β≤90° into a low-rate region, a medium-rate region and a high-rate region in the direction from the equator to the North Pole; wherein the latitude range of the low-rate region is 0°≤β<10°, the latitude range of the medium-rate region is 10°≤β<30°, and the latitude range of the high-rate region is 30°≤β≤90°; (2) Determine the etching times of the high-rate region, medium-rate region, low-rate region, and crystal hemisphere, which are T1, T2, T3, and T4, respectively; determine that the etching rate corresponding to the crystal plane (0001) in the high-rate region is v1, and the etching rate corresponding to the crystal plane (1-101) or (-2111) in the medium-rate region is v2, and T1:T2=v2 1 / 2 :v1 1 / 2 , T3 is (2-3) times T2, T4 = T2; (3) setting four crystal hemispheres of the same size, and setting the etching time of the high rate region, the medium rate region, the low rate region and the crystal hemisphere respectively, performing wet etching along the corresponding regions, and obtaining the ratio of the radial etching distance to the etching time, which is the etching rate of the corresponding coordinate point; (4) Referring to the etching rate of the crystal hemisphere corresponding to the etching time T4, the etching rate data of the high rate area, medium rate area, and low rate area corresponding to the etching times T1, T2, and T3 are synthesized to obtain the full crystal surface etching rate of the crystal.

2. The method for segmented measurement of crystal hemispherical wet etching rate according to claim 1, characterized in that: In step (3), when the wet etching is performed, the three-dimensional coordinates of the coordinate points are measured at intervals of 1-2° along the longitude direction of 0°≤α≤360° and the latitude direction of 0°≤β≤90°.

3. The method for segmented measurement of crystal hemispherical wet etching rate according to claim 1, characterized in that: A clamping device for placing four crystal hemispheres of the same size comprises a chassis (1) and a lifting rod (2) located at the center of the chassis. Positions on the chassis (1) corresponding to the placement of the crystal hemispheres are provided with a limiting assembly and a fixing assembly. The limiting assembly comprises a fixing pin (3) arranged on the upper end surface of the chassis (1) and a movable positioning pin assembly arranged on the chassis (1). A sliding groove (4) matching the movable positioning pin assembly is provided on the chassis (1).

4. The method for segmented measurement of crystal hemispherical wet etching rate according to claim 3, characterized in that: The movable positioning pin assembly comprises a sliding block (5) matched with a sliding groove (4) and a positioning pin (6) arranged on the sliding block (5); the crystal hemisphere is positioned and limited by the positioning pin (6) and the fixing pin (3).

5. The method for segmented measurement of crystal hemispherical wet etching rate according to claim 3, characterized in that: The fixing assembly comprises a sliding block (5) and a baffle (7) arranged at one end of the sliding block (5), and a sliding groove (4) matching the sliding block is provided on the chassis (1).

6. The method for segmented measurement of crystal hemispherical wet etching rate according to claim 4, characterized in that: The bottom end of the crystal hemisphere is provided with a groove which matches with the positioning pin (6) and the fixing pin (3).

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