A method of etch inspection of subsurface damage in polished indium arsenide wafers

Abstract

The application provides a method for etching detection of subsurface damage of polished indium arsenide wafers, comprising: pretreating the polished indium arsenide wafers to obtain pretreated polished indium arsenide wafers; etching the pretreated polished indium arsenide wafers in a first etching solution for a preset time to obtain polished indium arsenide wafers etched by the first etching solution, wherein the first etching solution is prepared from phosphoric acid and hydrogen peroxide; etching the polished indium arsenide wafers etched by the first etching solution in a second etching solution for a preset time to obtain polished indium arsenide wafers etched by the second etching solution, wherein the second etching solution is prepared from hydrochloric acid and water; cleaning and drying the polished indium arsenide wafers etched by the second etching solution, and then observing the polished indium arsenide wafers etched by the second etching solution under a microscope to determine the number and distribution of surface etching pits of the polished indium arsenide wafers etched by the second etching solution.

Description

Technical Field

[0001] This invention relates to the field of defect detection technology, and in particular to a corrosion detection method for subsurface damage in polished indium arsenide wafers. Background Technology

[0002] Indium arsenide (IAR), a narrow-bandgap III-V compound semiconductor material with a bandgap of 0.36 eV at room temperature, has wide applications in infrared optoelectronics. Indium arsenide can be used as a substrate to grow heterojunction materials such as InAsSb and InNAsSb, thereby fabricating infrared light-emitting devices with wavelengths ranging from 2 to 14 μm. Furthermore, due to the good lattice constant matching between IAR and Sb-based ternary and quaternary alloys, IAR can serve as a substrate material for mid-infrared quantum cascade lasers and infrared detectors. These infrared devices show promising applications in gas detection, medicine, defense, and satellite communications.

[0003] To ensure the quality of the epitaxial layer and obtain excellent device performance, a damage-free indium arsenide (IAR) substrate material is required. The preparation of a high-quality substrate is closely related to the wafer fabrication process. However, IAR wafers develop residual damage after chemical mechanical polishing, forming a subsurface damage layer in the near-surface region. The characterization of this subsurface damage layer has a significant impact on improving the polishing process of IAR wafers and achieving high-quality epitaxy. Therefore, research on evaluating the subsurface damage of IAR wafers is of considerable importance. Summary of the Invention

[0004] In view of this, in order to enable rapid analysis of subsurface damage of indium arsenide wafers and provide effective suggestions for the improvement of polishing process, the present invention provides a corrosion detection method for subsurface damage of polished indium arsenide wafers.

[0005] To achieve the above objectives, the present invention provides a corrosion detection method for subsurface damage of polished indium arsenide wafers, the method comprising: pre-treating the polished indium arsenide wafers to obtain pre-treated polished indium arsenide wafers;

[0006] The pretreated polished indium arsenide wafer is placed in a first etching solution for a preset time to obtain a polished indium arsenide wafer after etching with the first etching solution, wherein the first etching solution is prepared from phosphoric acid and hydrogen peroxide.

[0007] The polished indium arsenide wafer, after being etched by the first etchant, is placed in the second etchant for a preset time to obtain the polished indium arsenide wafer after being etched by the second etchant. The second etchant is prepared by hydrochloric acid and water.

[0008] After the polished indium arsenide wafer was etched with the second etchant, it was cleaned and dried. Then, the polished indium arsenide wafer was observed under a microscope to determine the number and distribution of shallow corrosion pits on the surface of the polished indium arsenide wafer after etching with the second etchant. The number of shallow corrosion pits represents the degree of subsurface damage to the polished indium arsenide wafer, and the distribution of shallow corrosion pits represents the distribution of subsurface damage to the polished indium arsenide wafer.

[0009] According to an embodiment of the present invention, after pre-treating the polished indium arsenide wafer to obtain a pre-treated polished indium arsenide wafer, the method further includes: weighing the pre-treated polished indium arsenide wafer to obtain the initial weight of the pre-treated polished indium arsenide wafer.

[0010] According to an embodiment of the present invention, after obtaining the polished indium arsenide wafer etched by the first etchant, the process further includes:

[0011] After the polished indium arsenide wafer was etched by the first etching solution, it was cleaned and dried, and then weighed to obtain the weight of the polished indium arsenide wafer after the first etching solution.

[0012] The corrosion weight difference of the polished indium arsenide wafer is obtained by using the initial weight of the pretreated polished indium arsenide wafer and the weight of the polished indium arsenide wafer after etching with the first etching solution.

[0013] According to an embodiment of the present invention, the volume ratio of phosphoric acid to hydrogen peroxide in the first corrosive solution is (1-5):(1-3); and the volume ratio of hydrochloric acid to water in the second corrosive solution is (1-10):(0-1).

[0014] According to an embodiment of the present invention, the corrosion time in the first corrosive solution is preset to be 1 to 20 minutes; the corrosion time in the second corrosive solution is preset to be 1 to 5 minutes.

[0015] According to an embodiment of the present invention, the corrosion temperature of the first corrosive liquid and the corrosion temperature of the second corrosive liquid are both 20 to 50°C.

[0016] According to an embodiment of the present invention, the polished indium arsenide wafer is obtained by performing chemical mechanical polishing on a specific single side of the indium arsenide wafer.

[0017] According to an embodiment of the present invention, the crystal orientation of the indium arsenide wafer is (100).

[0018] According to an embodiment of the present invention, the microstructure of the corrosion pit is such that the long axis is parallel to the main positioning edge of the indium arsenide wafer.

[0019] According to an embodiment of the present invention, the cleaning and drying of the polished indium arsenide wafer after etching with the second etching solution includes:

[0020] The polished indium arsenide wafer after being etched by the second etching solution was rinsed with deionized water a preset number of times to obtain a cleaned polished indium arsenide wafer after being etched by the second etching solution.

[0021] The indium arsenide wafer, after being cleaned and etched by the second etching solution, was dried by blowing it with nitrogen gas.

[0022] According to an embodiment of the present invention, after etching the polished indium arsenide wafer with a first etchant, a second etchant is used to etch the polished indium arsenide wafer after etching with the first etchant. The number and distribution of shallow corrosion pits on the surface of the polished indium arsenide wafer are then observed under a microscope. This achieves a corrosion detection method that is simple to operate, highly efficient, and quickly and clearly displays the subsurface damage of the polished indium arsenide wafer. Furthermore, the damage depth of the subsurface damage layer of the polished indium arsenide wafer is estimated, providing effective guidance and reference for the improvement of the polishing process of arsenide steel. Attached Figure Description

[0023] Figure 1 This is a flowchart of a corrosion detection method according to an embodiment of the present invention;

[0024] Figure 2 This is a microscopic morphology image of an indium arsenide wafer after polishing according to Example 1 of the present invention, after being etched by a first etching solution for 1 minute and then by a second etching solution for 5 minutes.

[0025] Figure 3 This is a microscopic morphology image of an indium arsenide wafer after polishing according to Embodiment 1 of the present invention, after being etched with a first etching solution for 5 minutes and then with a second etching solution for 5 minutes.

[0026] Figure 4 This is a microscopic morphology image of an indium arsenide wafer after polishing according to Example 1 of the present invention, after being etched with a first etching solution for 10 minutes and then with a second etching solution for 5 minutes.

[0027] Figure 5 This is a microscopic morphology image of an indium arsenide wafer after polishing according to Example 1 of the present invention, after being etched with a first etching solution for 20 minutes and then with a second etching solution for 5 minutes.

[0028] Figure 6 This is a microscopic morphology image of an indium arsenide wafer after polishing according to Embodiment 3 of the present invention, after being etched by a first etching solution for 1 minute and then by a second etching solution for 1 minute.

[0029] Figure 7The image shows the microstructure of the polished indium arsenide wafer in Comparative Example 1 after being etched with the third etching solution for 5 minutes. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0031] Figure 1 This is a flowchart of a corrosion detection method according to an embodiment of the present invention.

[0032] like Figure 1 As shown, the method may include operations S110 to S140.

[0033] In operation S110, the polished indium arsenide wafer is pretreated to obtain a pretreated polished indium arsenide wafer.

[0034] According to an embodiment of the present invention, the polished indium arsenide wafer can be obtained by chemical mechanical polishing of a specific single side of an indium arsenide single wafer.

[0035] According to an embodiment of the present invention, a specific single side of the indium arsenide single wafer can be a side that needs to be polished. There is no specific designation of which side it is, and it can be selected according to actual needs. No limitation is made here.

[0036] According to embodiments of the present invention, chemical mechanical polishing (CMP) can be performed on multiple surfaces of an indium arsenide single wafer without the need for such polishing. CMP is performed using a conventional polishing machine, and the specific methods are the same as those used in existing CMP systems, and will not be described further here.

[0037] According to an embodiment of the present invention, the indium arsenide single crystal wafer can be selected from the cut wafer obtained by cutting an indium arsenide single crystal ingot with a crystal face of (100) and a size of 2 inches.

[0038] According to an embodiment of the present invention, an indium arsenide wafer with a crystal plane of (100) is more suitable for subsequent etching solution, which can effectively etch and illustrate the condition of its etching pits.

[0039] According to an embodiment of the present invention, pretreatment of polished indium arsenide wafers may include: sealing the unpolished surfaces of the indium arsenide wafers other than the polished surfaces with wax, and leaving the polished surfaces of the indium arsenide wafers unsealed with wax in the air for corrosion detection.

[0040] In operation S120, the pre-treated polished indium arsenide wafer is placed in a first etching solution for a preset time to obtain a polished indium arsenide wafer after etching with the first etching solution, wherein the first etching solution is prepared from phosphoric acid and hydrogen peroxide.

[0041] According to an embodiment of the present invention, the first corrosive solution can be prepared by mixing phosphoric acid and hydrogen peroxide in different volume ratios. During the preparation process, continuous stirring is required to ensure that the phosphoric acid solution and the hydrogen peroxide solution are fully mixed.

[0042] According to embodiments of the present invention, the volume ratio of phosphoric acid to hydrogen peroxide solution can be (1-5):(1-3). Preferably, it can be 1:1, 2:1, 3:2, or 1:5.

[0043] According to an embodiment of the present invention, the preset corrosion time in the first corrosive solution can be 1 to 20 minutes. Preferably, it can be 1 minute, 5 minutes, 10 minutes, or 20 minutes.

[0044] According to an embodiment of the present invention, the polished indium arsenide wafer can be placed in a dry basket and slowly immersed in a first etching solution, and etched for 1 min, 5 min, 10 min and 20 min respectively to obtain the polished indium arsenide wafer with the corresponding etching time.

[0045] According to an embodiment of the present invention, after etching the polished indium arsenide wafer with a first etching solution for a preset time, polished indium arsenide wafers etched with the first etching solution for different times can be obtained respectively.

[0046] In operation S130, the polished indium arsenide wafer after being etched by the first etchant is placed in the second etchant for a preset time to obtain the polished indium arsenide wafer after being etched by the second etchant, wherein the second etchant is prepared by hydrochloric acid and water.

[0047] According to an embodiment of the present invention, the second corrosive solution can be prepared by mixing hydrochloric acid and water in different volume ratios. During the preparation process, continuous stirring is required to ensure that the hydrochloric acid and water are fully mixed.

[0048] According to an embodiment of the present invention, the volume ratio of hydrochloric acid to water in the solution can be (1-10):(0-1). It should be noted that when the volume of the aqueous solution is 0, the second corrosive solution can be hydrochloric acid, and the aqueous solution can be deionized water.

[0049] According to embodiments of the present invention, the volume ratio of hydrochloric acid to water in the second corrosive solution can preferably be 10:1, 9:1, or 4:1.

[0050] According to an embodiment of the present invention, the preset corrosion time in the second corrosive solution can be 1 to 5 minutes.

[0051] According to an embodiment of the present invention, the corrosion preset time can preferably be 1 min, 3 min, or 5 min.

[0052] According to embodiments of the present invention, polished indium arsenide wafers etched with a first etchant for different times can be placed in a dry basket and slowly immersed in a second etchant for different times. For example, polished indium arsenide wafers etched with the first etchant for 5 minutes can be immersed in the second etchant for different times (e.g., 1 minute, 3 minutes, 5 minutes); polished indium arsenide wafers etched with the first etchant for 10 minutes can be immersed in the second etchant for different times (e.g., 1 minute, 3 minutes, 5 minutes), and so on. The etching process of etching polished indium arsenide wafers etched with the first etchant for different times and then etching them in the second etchant for different times will not be described in detail here.

[0053] According to an embodiment of the present invention, the corrosion temperature of the first corrosive liquid and the corrosion temperature of the second corrosive liquid can both be set to 20-50°C.

[0054] According to embodiments of the present invention, the corrosion temperature can be 20°C, 30°C, 40°C, or 50°C.

[0055] According to embodiments of the present invention, a suitable corrosion temperature is a necessary condition for clearly revealing crystal structure defects. If the corrosion temperature is too low, the chemical reaction rate is slow, and the corrosion efficiency will be greatly reduced; if the corrosion temperature is too high, the corrosion rate is too fast, the reactants cannot dissolve in time, and a large amount of reactants accumulate on the material surface, which will affect the corrosion effect. In addition, selecting a suitable corrosion temperature to ensure a moderate corrosion rate is beneficial for weighing and calculating the corrosion thickness.

[0056] According to an embodiment of the present invention, after etching the polished indium arsenide wafer etched by the first etchant for a preset time using the second etchant, polished indium arsenide wafers etched by the second etchant for different times can be obtained respectively.

[0057] In operation S140, after cleaning and drying the polished indium arsenide wafer etched by the second etchant, the polished indium arsenide wafer etched by the second etchant is observed under a microscope to determine the number and distribution of shallow corrosion pits on the surface of the polished indium arsenide wafer etched by the second etchant. The number of shallow corrosion pits represents the degree of subsurface damage to the polished indium arsenide wafer, and the distribution of shallow corrosion pits represents the distribution of subsurface damage to the polished indium arsenide wafer.

[0058] According to an embodiment of the present invention, cleaning and drying the polished indium arsenide wafer after etching with the second etchant may include: rinsing the polished indium arsenide wafer after etching with the second etchant a predetermined number of times with deionized water to obtain a cleaned polished indium arsenide wafer after etching with the second etchant; and then drying the cleaned polished indium arsenide wafer after etching with nitrogen gas.

[0059] According to an embodiment of the present invention, the polished indium arsenide wafer, after being etched by the second etching solution, can be quickly removed from the second etching solution, rinsed with deionized water 4 to 5 times, and then the surface of the polished indium arsenide wafer can be dried with nitrogen gas to achieve the drying of the polished indium arsenide wafer.

[0060] According to an embodiment of the present invention, an optical microscope can be used to observe polished indium arsenide wafers after different etching times. When polished indium arsenide wafers after different etching times are placed under an optical microscope and magnified 100 times, the number and distribution of etching pits on the polished indium arsenide wafers after etching by the first etching solution and the second etching solution can be determined by microscopic observation of the polished indium arsenide wafers.

[0061] According to embodiments of the present invention, corrosion pits may include dislocation pits and shallow corrosion pits. Dislocation pits are corrosion pits that are few in number and have sharp points inside, and are mainly related to the thermal stress during the growth process of indium arsenide wafers.

[0062] According to an embodiment of the present invention, the etching pits are numerous and densely distributed shallow flat-bottomed pits on the surface of the indium arsenide wafer. The microstructure of the etching pits can be such that the long axis of the pit is parallel to the main positioning edge of the indium arsenide wafer, that is, the

[110] direction of the indium arsenide wafer can be used as the main positioning edge of the wafer. It should be noted that the main positioning edge can be determined by existing methods in the art for determining the main positioning edge of the wafer, which will not be elaborated here.

[0063] According to an embodiment of the present invention, after chemical mechanical polishing of an indium arsenide wafer, damage residues will be generated in the near-surface region of the indium arsenide wafer, forming a subsurface damage layer with a certain thickness. Subsurface damage is a defect caused by wafer processing. The degree of subsurface damage of the indium arsenide wafer affects the performance of the epitaxial device it generates. Therefore, it is necessary to perform corrosion detection on the subsurface damage of the indium arsenide wafer to characterize the degree of subsurface damage of the indium arsenide wafer.

[0064] According to an embodiment of the present invention, the number of shallow corrosion pits characterizes the degree of subsurface damage to the indium arsenide wafer after polishing, and the distribution of shallow corrosion pits characterizes the distribution of subsurface damage to the indium arsenide wafer after polishing.

[0065] According to embodiments of the present invention, the greater the number of corrosion pits, the greater the subsurface damage of the polished indium arsenide wafer with a larger number of pits; the denser the distribution of corrosion pits and the wider their distribution on the wafer surface, the greater the subsurface damage of the polished indium arsenide wafer where the pits are densely distributed; and the wider the distribution of pits, the wider the range of subsurface damage of the polished indium arsenide wafer.

[0066] According to an embodiment of the present invention, after etching the polished indium arsenide wafer with a first etchant, a second etchant is then used to etch the polished indium arsenide wafer after etching with the first etchant. The number and distribution of shallow corrosion pits on the surface of the polished indium arsenide wafer are then observed under a microscope. This achieves a simple and efficient corrosion detection method that quickly and clearly displays the subsurface damage of the polished indium arsenide wafer and estimates the damage depth of the subsurface damage layer of the polished indium arsenide wafer, providing effective guidance and reference for the improvement of the indium arsenide polishing process.

[0067] According to an embodiment of the present invention, after pre-treating the polished indium arsenide wafer to obtain the pre-treated polished indium arsenide wafer, the method may further include: weighing the pre-treated polished indium arsenide wafer to obtain the initial weight of the pre-treated polished indium arsenide wafer.

[0068] According to an embodiment of the present invention, in conjunction with the description in step S110 above, after sealing the unpolished surface and the side of the polished indium arsenide wafer with wax, the polished surface is placed in the air, and the polished indium arsenide wafer after sealing with wax is weighed using an electronic balance, and the initial weight of the polished indium arsenide wafer after sealing with wax is recorded.

[0069] According to an embodiment of the present invention, the initial weight of the polished indium arsenide wafer after wax sealing can indicate the weight of the polished indium arsenide wafer before it is etched by the first etchant.

[0070] According to an embodiment of the present invention, the accuracy of the electronic balance can be 0.1 mg.

[0071] According to an embodiment of the present invention, after recording the initial weight of the polished indium arsenide wafer after sealing with wax, and then placing the polished indium arsenide wafer in a first etchant for a preset time to obtain the polished indium arsenide wafer after etching with the first etchant, the process may further include: cleaning and drying the polished indium arsenide wafer after etching with the first etchant, weighing the polished indium arsenide wafer after etching with the first etchant to obtain the weight of the polished indium arsenide wafer after etching with the first etchant; and obtaining the etching weight difference of the polished indium arsenide wafer using the initial weight of the pretreated polished indium arsenide wafer and the weight of the polished indium arsenide wafer after etching with the first etchant.

[0072] According to an embodiment of the present invention, after polishing, indium arsenide wafers are placed in a first etching solution for different etching times, and then cleaned and dried. The polished indium arsenide wafers after different etching times are weighed using an electronic balance to obtain the weight of the polished indium arsenide wafers after etching with the first etching solution.

[0073] According to an embodiment of the present invention, it should be noted that after the wax sealing pretreatment, the first and second etchants do not affect the corrosion of the wax when they etch the polished indium arsenide wafer.

[0074] According to embodiments of the present invention, the initial weight of the pretreated and polished indium arsenide wafer and the weight of the polished indium arsenide wafer after etching with the first etching solution can be calculated for different etching times, and the difference in etched weight of the polished indium arsenide wafer at different etching times can be determined.

[0075] According to an embodiment of the present invention, when the first etchant etches the polished indium arsenide wafer, it is a process of continuously peeling off the subsurface damage layer of the polished indium arsenide. The amount of damage layer peeled off can be reflected by the difference in the etched weight of the polished indium arsenide wafer. Specifically, the thickness of the peeled subsurface damage layer of the polished indium arsenide (i.e., the thickness removed after etching the polished indium arsenide wafer) can be obtained by dividing the difference in the etched weight of the polished indium arsenide wafer by the density of the indium arsenide wafer, and then dividing by the area of ​​the indium arsenide wafer. The thickness of the peeled subsurface damage layer can reflect the depth of the subsurface damage.

[0076] According to an embodiment of the present invention, when the polished indium arsenide after being etched by the first etchant is then etched by the second etchant, and no shallow pits are observed using an optical microscope, the difference in etch weight of the polished indium arsenide wafer after being etched by the first etchant can be used to characterize the damaged layer that has been stripped by the etch, that is, the thickness of the wafer damaged layer removed. The thickness of the wafer damaged layer removed can be considered as the depth of the subsurface damaged layer.

[0077] To further illustrate the present invention, the corrosion detection method and microstructure of subsurface damage on polished indium arsenide wafers provided by the present invention are described in detail below with reference to specific embodiments and comparative examples. However, it should be understood that these embodiments are merely illustrative to aid in understanding the inventive concept and are not intended to limit the scope of the claims of the present invention, nor are they limited to the following embodiments.

[0078] Example 1

[0079] A corrosion detection method for subsurface damage on polished indium arsenide wafers may include:

[0080] Step 1: Select indium arsenide wafers.

[0081] Specifically, an indium arsenide wafer is obtained by cutting a 2-inch (100) crystal ingot of indium arsenide.

[0082] Step 2: Perform single-sided chemical mechanical polishing on the selected arsenide steel single crystal to obtain the polished arsenide steel single crystal.

[0083] Specifically, the indium arsenide wafer is subjected to single-sided chemical mechanical polishing using a polishing machine to obtain the polished indium arsenide wafer.

[0084] Step 3: Pre-treat the sides and unpolished surfaces of the polished indium arsenide wafer, and record the initial weight of the pre-treated polished indium arsenide wafer using an electronic balance.

[0085] Specifically, the sides and unpolished surfaces of the polished indium arsenide wafer were sealed with wax, and the initial weight of the polished indium arsenide wafer after sealing with wax was recorded using an electronic balance with an accuracy of 0.1 mg.

[0086] Step 4: Place the pre-treated polished indium arsenide wafer in the first etching solution for a preset time to obtain the polished indium arsenide wafer after etching with the first etching solution.

[0087] Specifically,

[0088] (1) The first etching solution is prepared at room temperature using phosphoric acid and hydrogen peroxide, wherein the volume ratio of phosphoric acid solution to hydrogen peroxide solution is 1:1. During the preparation of the first etching solution, it is necessary to stir continuously to ensure that the phosphoric acid solution and hydrogen peroxide solution are fully mixed.

[0089] (2) Place the polished indium arsenide wafer into a dry basket and slowly place it into the prepared first etching solution for etching times of 1 min, 5 min, 10 min and 20 min respectively, to obtain the polished indium arsenide wafer after etching with the first etching solution for the corresponding etching time.

[0090] Step 5: After cleaning and drying the polished indium arsenide wafer after etching with the first etching solution, weigh the polished indium arsenide wafer after etching with the first etching solution to obtain the weight of the polished indium arsenide wafer after etching with the first etching solution.

[0091] Specifically, (1) the polished indium arsenide wafers after being etched by the first etchant for different times were quickly taken out and rinsed with deionized water 4-5 times. Then the wafer surface was dried with nitrogen gas. The weight of the polished indium arsenide wafers after being etched by the first etchant for different times was recorded by an electronic balance with an accuracy of 0.1 mg.

[0092] (2) Using the initial weight and the weight of the polished indium arsenide wafer after different etching times by the first etching solution, the etching weight difference for each etching time is calculated.

[0093] Specifically, the thickness of the subsurface damage layer after polishing can be obtained by dividing the difference in corrosion weight of the polished indium arsenide wafer by the density of the indium arsenide wafer, and then by the area of ​​the indium arsenide wafer. This thickness reflects the depth of the subsurface damage.

[0094] For example, Table 1 shows the thickness values ​​removed from polished indium arsenide wafers after etching with the first etchant for different times.

[0095] Table 1

[0096] Corrosion time 1min 5min 10min 20min Thickness value removed 1.78μm 8.45μm 14.58μm 28.94μm

[0097] Step 6: Place the polished indium arsenide wafer after etching with the first etching solution into the second etching solution for a preset time to obtain the polished indium arsenide wafer after etching with the second etching solution.

[0098] Specifically, (1) the second etching solution is prepared at room temperature using hydrochloric acid and deionized water, wherein the volume ratio of hydrochloric acid to deionized water is 10:1. During the preparation of the second etching solution, it is necessary to stir continuously so that the hydrochloric acid solution and deionized water are fully mixed.

[0099] (2) The polished indium arsenide wafers after being etched by the first etchant for different times were placed in a dry basket and slowly placed in the prepared second etchant for 5 minutes to obtain polished indium arsenide wafers after being etched by the first etchant for different times and then etched by the second etchant.

[0100] Step 7: After cleaning and drying the polished indium arsenide wafer after etching with the second etching solution, perform microscopic observation on the polished indium arsenide wafer after etching with the second etching solution to determine the number and distribution of shallow corrosion pits on the surface of the polished indium arsenide wafer after etching with the second etching solution.

[0101] Specifically, the polished indium arsenide wafer, after being etched by the second etching solution, was quickly removed and rinsed 4-5 times with deionized water. The wafer surface was then dried with nitrogen gas, and the number and distribution of shallow etching pits on the polished indium arsenide wafer surface were observed using an optical microscope. A shallow etching pit is a type of pit whose long axis is parallel to the main positioning edge of the wafer (i.e., [1]). 0] direction, in Figure 2 The surface defects (already marked) are consistent in orientation and morphology of each corrosion pit in each micrograph. The number and distribution of corrosion pits can be used to characterize the degree and distribution of subsurface damage.

[0102] For example, Figure 2 This is a microscopic morphology image of an indium arsenide wafer after polishing according to Example 1 of the present invention, after being etched by a first etching solution for 1 minute and then by a second etching solution for 5 minutes. Figure 3 This is a microscopic morphology image of an indium arsenide wafer after polishing according to Embodiment 1 of the present invention, after being etched with a first etching solution for 5 minutes and then with a second etching solution for 5 minutes. Figure 4This is a microscopic morphology image of an indium arsenide wafer after polishing according to Example 1 of the present invention, after being etched with a first etching solution for 10 minutes and then with a second etching solution for 5 minutes. Figure 5 This is a microscopic morphology image of an indium arsenide wafer after polishing according to Example 1 of the present invention, after being etched by a first etching solution for 20 minutes and then by a second etching solution for 5 minutes.

[0103] Combination Figures 2-5 The microstructures of polished indium arsenide wafers are shown below after etching with a first etchant for different times and then with a second etchant for 5 minutes. Figures 2 to 5 It can be seen that after etching with the first etchant for different durations, followed by etching with the second etchant for the same duration, numerous densely distributed shallow pits appear. The larger and more numerous the shallow pits, the greater the degree of damage. Furthermore, the size and number of these shallow pits decrease with increasing etching time with the first etchant, indicating that the subsurface damage layer of the indium arsenide wafer is gradually removed after polishing. Figure 3 and Figure 4 It can be seen that, in addition to the presence of shallow corrosion pits, there are also a small number of dislocation pits with internal sharp points. The presence of these dislocation pits is related to the thermal stress during the growth of indium arsenide crystals. After etching with the first etchant for 20 minutes and then with the second etchant for 5 minutes, the microstructure images show almost no shallow corrosion pits (e.g., Figure 5 As shown in the figure, the thickness removed after 20 minutes of etching with the first etchant can be approximated as the depth of the subsurface damage layer. For example, according to Table 1, the thickness removed after 20 minutes of etching with the first etchant is 28.94 μm, so the depth of the subsurface damage layer of the indium arsenide wafer caused by polishing can be approximated as 28.94 μm.

[0104] Example 2

[0105] The corrosion detection method in this embodiment 2 differs from that in step 4 of embodiment 1 when preparing the first corrosion solution, in that the volume ratio of phosphoric acid to hydrogen peroxide solution is different, and the volume ratio of hydrochloric acid to deionized water solution is different from that in step 6 of embodiment 1 when preparing the second corrosion solution. All other steps are the same, and will not be repeated in this embodiment 2.

[0106] In Example 2, when preparing the first etching solution, the volume ratio of phosphoric acid to hydrogen peroxide was 3:2; when preparing the second etching solution, the volume ratio of hydrochloric acid to deionized water was 9:1.

[0107] In this Example 2, after being etched with the first etchant for different times and then etched with the second etchant for the same time, the polished indium arsenide wafer was placed under an optical microscope and magnified to the same magnification as in Example 1. It can be observed that the morphology of the shallow corrosion pits on the surface of the indium arsenide wafer is the same as that in Example 1. Therefore, microscopic images are not provided here.

[0108] Example 3

[0109] The corrosion detection method in this embodiment 3 differs from that in embodiment 1, step 6, where the corrosion time is different after 1 minute of corrosion with the first corrosive liquid followed by corrosion with the second corrosive liquid. All other steps are the same, and will not be repeated in this embodiment 2.

[0110] In Example 3, when preparing the first etching solution, the volume ratio of phosphoric acid to hydrogen peroxide solution is 1:1; when preparing the second etching solution, the volume ratio of hydrochloric acid to deionized water solution is 10:1. After etching with the first etching solution for 1 minute, the wafer is then etched with the second etching solution for 1 minute to obtain a polished indium arsenide wafer after etching with the second etching solution.

[0111] The polished indium arsenide wafer, after being etched by the second etching solution, was placed under an optical microscope for microscopic observation to determine the microstructure of the polished indium arsenide wafer.

[0112] For example, Figure 6 This is a microscopic morphology image of an indium arsenide wafer after polishing according to Embodiment 3 of the present invention, after being etched by a first etching solution for 1 minute and then by a second etching solution for 1 minute.

[0113] from Figure 6 It can be seen that, with Figure 2 Compared with the microscopic morphology, it can be observed that when the etching time of the second etching solution is shorter, the size of the shallow pits obtained by etching is smaller, but the shallow pits can still be clearly shown, which can be used to characterize the subsurface damage degree of the indium arsenide wafer.

[0114] Comparative Example 1

[0115] As a comparative example, a third etching solution was prepared with a volume ratio of hydrochloric acid, nitric acid, and deionized water of 1:2:1. In this comparative example, the polished indium arsenide wafer was not etched by the first etching solution, but only by the third etching solution. Specifically, this process may include the following steps:

[0116] Step 1: Select indium arsenide wafers.

[0117] Specifically, an indium arsenide wafer is obtained by cutting a 2-inch (100) crystal ingot of indium arsenide.

[0118] Step 2: Perform single-sided chemical mechanical polishing on the selected indium arsenide single wafer to obtain the polished indium arsenide wafer.

[0119] Specifically, the indium arsenide wafer is subjected to single-sided chemical mechanical polishing using a polishing machine to obtain the polished indium arsenide wafer.

[0120] Step 3: Place the polished indium arsenide wafer directly into the etching solution for etching to obtain the etched polished indium arsenide wafer.

[0121] Specifically, (1) the third corrosion solution is prepared at room temperature using hydrochloric acid, nitric acid and deionized water, wherein the volume ratio of hydrochloric acid, nitric acid and deionized water is 1:2:1. During the preparation process, the solution needs to be stirred continuously to ensure that the solution is fully mixed.

[0122] (2) Place the polished indium arsenide single crystal wafer into a dry basket and slowly place it into the third etching solution prepared above. The etching time is 5 minutes to obtain the etched polished indium arsenide wafer.

[0123] Step 4: After cleaning and drying the polished indium arsenide wafer after etching with the third etching solution, perform microscopic observation on the polished indium arsenide wafer after etching with the third etching solution to determine the number and distribution of shallow corrosion pits on the surface of the polished indium arsenide wafer after etching with the third etching solution.

[0124] Specifically, the polished indium arsenide wafer, after being etched by the third etching solution, was quickly removed and rinsed with deionized water 4-5 times. Then, the wafer surface was dried with nitrogen gas, and the number and distribution of shallow corrosion pits on the surface of the polished indium arsenide wafer were observed using an optical microscope.

[0125] Specifically, the polished indium arsenide wafer, after being etched by the third etching solution, was quickly removed and rinsed with deionized water 4-5 times. Then, the wafer surface was dried with nitrogen gas, and the number and distribution of corrosion pits on the surface of the polished indium arsenide wafer were observed using an optical microscope.

[0126] For example, Figure 7 The image shows the microstructure of the polished indium arsenide wafer in Comparative Example 1 after being etched with the third etching solution for 5 minutes.

[0127] from Figure 7 As can be seen, circular corrosion patterns appear on the surface of the indium arsenide wafer after polishing following direct etching with the third etchant. These circular corrosion defects are related to the chemical reaction process on the surface of indium arsenide, and the resulting circular corrosion patterns do not have a specific shape or orientation. This indicates that the third etchant does not have selective corrosivity and cannot characterize the subsurface damage to the indium arsenide wafer after polishing.

[0128] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for detecting subsurface damage corrosion in polished indium arsenide wafers, comprising: The polished indium arsenide wafer is pretreated to obtain a pretreated polished indium arsenide wafer. The pretreated polished indium arsenide wafer is placed in a first etching solution for a preset time to obtain a polished indium arsenide wafer after etching with the first etching solution, wherein the first etching solution is prepared from phosphoric acid and hydrogen peroxide. The polished indium arsenide wafer, after being etched by the first etchant, is placed in a second etchant for a preset time to obtain a polished indium arsenide wafer etched by the second etchant, wherein the second etchant is prepared from hydrochloric acid and water. After cleaning and drying the polished indium arsenide wafer etched by the second etchant, the polished indium arsenide wafer etched by the second etchant is observed under a microscope to determine the number and distribution of the surface corrosion pits of the polished indium arsenide wafer etched by the second etchant. The number of corrosion pits represents the degree of subsurface damage of the polished indium arsenide wafer, and the distribution of corrosion pits represents the distribution of subsurface damage of the polished indium arsenide wafer.

2. The method according to claim 1, wherein, After pre-treating the polished indium arsenide wafer to obtain the pre-treated polished indium arsenide wafer, the process further includes: The pretreated and polished indium arsenide wafer is weighed to obtain the initial weight of the pretreated and polished indium arsenide wafer.

3. The method according to claim 2, wherein, After obtaining the polished indium arsenide wafer etched by the first etchant, the process further includes: After cleaning and drying the polished indium arsenide wafer after etching with the first etching solution, the indium arsenide wafer after etching with the first etching solution is weighed to obtain the weight of the polished indium arsenide wafer after etching with the first etching solution. The corrosion weight difference of the polished indium arsenide wafer is obtained by using the initial weight of the pretreated polished indium arsenide wafer and the weight of the polished indium arsenide wafer after etching with the first etching solution.

4. The method according to claim 1, wherein, The volume ratio of phosphoric acid to hydrogen peroxide in the first corrosive solution is (1-5):(1-3); the volume ratio of hydrochloric acid to water in the second corrosive solution is (1-10):(0-1).

5. The method according to claim 1, wherein, The preset corrosion time in the first corrosive solution is 1 to 20 minutes; the preset corrosion time in the second corrosive solution is 1 to 5 minutes.

6. The method according to claim 1, wherein, The corrosion temperature of both the first and second corrosive solutions is 20–50°C.

7. The method according to claim 1, wherein, The polished indium arsenide wafer is obtained by chemical mechanical polishing a specific single side of the indium arsenide wafer.

8. The method according to claim 7, wherein, The crystal orientation of the indium arsenide wafer is (100).

9. The method according to claim 7, wherein, The microstructure of the corrosion pits is such that the long axis is parallel to the main positioning edge of the indium arsenide wafer.

10. The method according to claim 1, wherein, The polished indium arsenide wafer, after being etched by the second etching solution, is then cleaned and dried, including: The polished indium arsenide wafer after being etched by the second etching solution was rinsed with deionized water a preset number of times to obtain a cleaned polished indium arsenide wafer after being etched by the second etching solution. The indium arsenide wafer, after being cleaned and etched by the second etching solution, was dried by blowing it with nitrogen gas.

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