Semiconductor epitaxial layer corrosion resistance calibration method

Abstract

The invention provides a semiconductor epitaxial layer corrosion resistance calibration method, and relates to the technical field of semiconductor testing. The method comprises the following steps: corroding an InGaP epitaxial layer by adopting an HCl corrosive liquid; observing the surface of the sample by using a microscope, and measuring to obtain data of the size of the circular corrosion pattern changing along with corrosion time; performing linear fitting on the data to obtain a linear function relationship; according to the linear function relation, the corresponding corrosion time when the graph size is zero is obtained through calculation. According to the method, the longest anti-corrosion time when the AlGaAs epitaxial layer is not penetrated can be calculated and speculated by measuring the change relation of the size of the corrosion pattern formed by the corrosive liquid penetrating through the AlGaAs epitaxial layer along with the time, and the calibration of the corrosion resistance of the AlGaAs epitaxial layer is realized, so that a basis is provided for the formulation of a device process.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor testing, and in particular to a method for calibrating the corrosion resistance of a semiconductor epitaxial layer. Background Art

[0002] In the GaAs-based pHEMT device structure, an AlGaAs material layer is usually used as a barrier layer, and an InGaP material layer on the AlGaAs material layer is used as a corrosion barrier layer. In the etching process, HCl etching solution is usually used to selectively remove the InGaP material layer. Although HCl etching solution has a high selectivity for InGaP and AlGaAs, since the AlGaAs material layer contains Al elements and the HCl etching solution is corrosive to Al, when the AlGaAs material layer is very thin, the time for etching and removing the InGaP material layer with HCl etching solution cannot be too long to avoid corrosion penetrating the AlGaAs material layer.

[0003] Therefore, it is necessary to propose a method to quantitatively characterize the corrosion resistance of the AlGaAs material layer to the HCl etching solution, so as to facilitate the optimization and determination of the corrosion time of the InGaP material layer. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calibrating the corrosion resistance of a semiconductor epitaxial layer in view of the above-mentioned deficiencies in the prior art, so as to solve the problem of calibrating the corrosion resistance of an AlGaAs epitaxial layer.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: The present invention provides a method for calibrating the corrosion resistance of a semiconductor epitaxial layer. The method uses a test sample to calibrate the corrosion resistance of an AlGaAs epitaxial layer. The structure of the sample includes a first InGaP epitaxial layer, an AlGaAs epitaxial layer on the first InGaP epitaxial layer, and a second InGaP epitaxial layer on the AlGaAs epitaxial layer. The method includes: Step a, using a pre-configured HCl etching solution to corrode the second InGaP epitaxial layer, wherein the etching duration is less than or equal to a reference time period, wherein the reference time period is an expected length of time for completely removing the second InGaP epitaxial layer using the HCl etching solution; Step b, observing the sample surface with a microscope and corroding the sample with HCl corrosive solution are performed alternately, and after a circular corrosion pattern is observed under the microscope, corrosion data of the size of the circular corrosion pattern changing with corrosion time is measured; Step c, performing linear fitting on the corrosion data to obtain a linear function relationship; Step d: According to the linear function relationship, the corresponding etching time when the size of the circular etching pattern is zero is calculated, and the etching time is used as the anti-corrosion time of the AlGaAs epitaxial layer.

[0006] Optionally, the AlGaAs epitaxial layer has a thickness in a range of greater than or equal to 2 nm and less than or equal to 20 nm.

[0007] Optionally, the composition range of Al in the AlGaAs epitaxial layer is greater than or equal to 0.1 and less than or equal to 0.3.

[0008] Optionally, in step b, the duration of each corrosion is in the range of greater than or equal to 1 min and less than or equal to 4 min.

[0009] Optionally, when observing with a microscope, the magnification of the microscope is 500 times or 1000 times.

[0010] Optionally, in step b, after the circular corrosion pattern is observed under a microscope, the position of the circular corrosion pattern is marked, and the corrosion data of the size of the marked circular corrosion pattern changing with corrosion time is measured; if multiple circular corrosion patterns are observed under the microscope, the circular corrosion pattern with the largest size is selected for position marking.

[0011] The beneficial effects of the present invention include: The semiconductor epitaxial layer corrosion resistance calibration method provided by the present invention comprises: step a, using a pre-configured HCl corrosion solution to corrode the second InGaP epitaxial layer, the corrosion duration is less than or equal to the reference time period, and the reference time period is the expected time length for completely removing the second InGaP epitaxial layer by using the HCl corrosion solution; step b, using a microscope to observe the sample surface and using the HCl corrosion solution to corrode the sample alternately, after observing the circular corrosion pattern under the microscope, measuring and obtaining the corrosion data of the size of the circular corrosion pattern changing with the corrosion time; step c, performing linear fitting on the corrosion data to obtain a linear function relationship; step d, according to the linear function relationship, calculating the corresponding corrosion time when the size of the circular corrosion pattern is zero, and using the corrosion time as the corrosion resistance time of the AlGaAs epitaxial layer. The method can calculate and infer the longest corrosion resistance time of the AlGaAs epitaxial layer without being penetrated by measuring the relationship between the size of the corrosion pattern formed by the corrosion solution penetrating the AlGaAs epitaxial layer and the time, so as to realize the calibration of the corrosion resistance of the AlGaAs epitaxial layer, thereby providing a basis for the formulation of device technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 A flow chart of a method for calibrating corrosion resistance of a semiconductor epitaxial layer provided by an embodiment of the present invention is shown; Figure 2 A schematic diagram of a circular corrosion pattern provided by an embodiment of the present invention is shown; Figure 3 A data graph showing the change in the size of the corrosion image with the corrosion time provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] In the GaAs-based pHEMT device structure, an AlGaAs material layer is usually used as a barrier layer, and an InGaP material layer on the AlGaAs material layer is used as a corrosion barrier layer. In the etching process, HCl etching solution is usually used to selectively remove the InGaP material layer. Although HCl etching solution has a high selectivity for InGaP and AlGaAs, since the AlGaAs material layer contains Al elements and the HCl etching solution is corrosive to Al, when the AlGaAs material layer is very thin, the time for etching and removing the InGaP material layer with HCl etching solution cannot be too long to avoid corrosion penetrating the AlGaAs material layer.

[0016] Therefore, it is necessary to propose a method to quantitatively characterize the corrosion resistance of the AlGaAs material layer to the HCl etching solution, so as to facilitate the optimization and determination of the corrosion time of the InGaP material layer.

[0017] like Figure 1 As shown, the present invention provides a method for calibrating the corrosion resistance of a semiconductor epitaxial layer. The method uses a test sample to calibrate the corrosion resistance of an AlGaAs epitaxial layer. The structure of the sample includes a first InGaP epitaxial layer, an AlGaAs epitaxial layer on the first InGaP epitaxial layer, and a second InGaP epitaxial layer on the AlGaAs epitaxial layer.

[0018] Optionally, the thickness of the AlGaAs epitaxial layer is in a range of greater than or equal to 2 nm and less than or equal to 20 nm. Optionally, the composition of Al in the AlGaAs epitaxial layer is in a range of greater than or equal to 0.1 and less than or equal to 0.3.

[0019] The method comprises: Step a, using a pre-configured HCl etching solution to corrode the second InGaP epitaxial layer, wherein the etching duration is less than or equal to a reference time period, and the reference time period is the expected length of time for completely removing the second InGaP epitaxial layer using the HCl etching solution.

[0020] Step b, observing the sample surface with a microscope and corroding the sample with HCl corrosive solution are performed alternately. After the circular corrosion pattern is observed under the microscope, corrosion data of the size of the circular corrosion pattern changing with the corrosion time is measured.

[0021] Specifically, a microscope can be used to observe the surface of the sample after etching in step a, and then the sample can be further corroded using HCl etching solution, and then observed under a microscope, and then further corroded until a circular corrosion pattern is observed under the microscope. After the circular corrosion pattern is observed under the microscope, the corrosion is continued, and the size of the corrosion pattern (that is, the diameter of the circular corrosion pattern) is measured under a microscope at regular intervals, so that corrosion data of the size of the circular corrosion pattern changing with the corrosion time can be measured.

[0022] After the HCl etching solution completely removes the second InGaP epitaxial layer, the surface of the sample is the AlGaAs epitaxial layer. Since the HCl etching solution is corrosive to Al, the HCl etching solution will slowly corrode and penetrate the AlGaAs epitaxial layer. Before the HCl etching solution completely penetrates the AlGaAs epitaxial layer, the surface is observed to be flat and free of corrosion marks under the microscope. When some points in the AlGaAs epitaxial layer are corroded and penetrated, the HCl etching solution will reach the surface of the first InGaP epitaxial layer through the corrosion holes in the AlGaAs epitaxial layer, thereby continuing to corrode the first InGaP epitaxial layer. At this time, circular corrosion patterns will be observed under the microscope. As the corrosion time increases, the size of these circular corrosion patterns increases. Within a certain time range, the relationship between the size of these corrosion patterns and the corrosion time is approximately linear. Figure 2 As shown, in Figure 2 In the figure, the circular figures are all observed corrosion figures, which are the figures formed after the first InGaP epitaxial layer is etched. For example, the circular solid line 20 is the corrosion figure observed after a certain period of etching, and the circular dotted line 21 is the corrosion figure observed after further increasing the etching time. As the etching time increases, in addition to the increase in the size of the previous corrosion figure, new corrosion figures will be observed.

[0023] Optionally, in step b, the duration of each corrosion is in the range of greater than or equal to 1 minute and less than or equal to 4 minutes. For example, 3 to 5 corrosions may be performed. Optionally, when observing with a microscope, the magnification of the microscope is 500 times or 1000 times. Optionally, in step b, after observing the circular corrosion pattern under the microscope, the position of the circular corrosion pattern is marked, and the corrosion data of the size of the marked circular corrosion pattern changing with the corrosion time is measured. If multiple circular corrosion patterns are observed under the microscope, the circular corrosion pattern with the largest size is selected for position marking. Figure 2 As shown in FIG. 1 , the mark 22 is only used to locate the position of the circular corrosion pattern, so as to facilitate the observation of the change in the size of the pattern at the same position during the next microscope observation. The mark 22 can be, for example, a scratch on the surface of the sample or other patterns that are easy for the human eye to recognize. Figure 2 The mark 22 shown in the figure is a cross shape. It should be understood that the present application does not limit the specific shape of the mark 22.

[0024] Step c: performing linear fitting on the corrosion data to obtain a linear function relationship.

[0025] Step d: According to the linear function relationship, the corresponding etching time when the size of the circular etching pattern is zero is calculated, and the etching time is used as the anti-corrosion time of the AlGaAs epitaxial layer.

[0026] like Figure 3 As shown in the figure, the size of the corrosion pattern at the same point is observed and measured multiple times under a microscope to form measurement data ( Figure 3 The black box in the figure), after linear fitting, the linear function relationship is obtained, and then the corrosion time t0 corresponding to the size of the circular corrosion pattern is calculated. Figure 3 According to the data in, the corrosion time t0 can be used as the corrosion resistance time of the AlGaAs epitaxial layer.

[0027] By measuring the relationship between the size of the corrosion pattern formed by the corrosion liquid penetrating the AlGaAs epitaxial layer and the time change, the method can calculate and infer the longest corrosion resistance time of the AlGaAs epitaxial layer without being penetrated, realize the calibration of the corrosion resistance of the AlGaAs epitaxial layer, and thus provide a basis for the formulation of device technology.

[0028] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calibrating the corrosion resistance of a semiconductor epitaxial layer, characterized in that: The method uses a test sample to calibrate the corrosion resistance of the AlGaAs epitaxial layer, the structure of the sample includes a first InGaP epitaxial layer, an AlGaAs epitaxial layer on the first InGaP epitaxial layer, and a second InGaP epitaxial layer on the AlGaAs epitaxial layer, and the method includes: Step a, using a pre-configured HCl etching solution to corrode the second InGaP epitaxial layer, wherein the etching duration is less than or equal to a reference time period, wherein the reference time period is an expected length of time for completely removing the second InGaP epitaxial layer using the HCl etching solution; Step b, observing the sample surface with a microscope and corroding the sample with HCl corrosive solution are performed alternately, and after a circular corrosion pattern is observed under the microscope, data of the change of the size of the circular corrosion pattern with the corrosion time is measured; Step c, performing linear fitting on the data to obtain a linear function relationship; Step d: According to the linear function relationship, the corresponding etching time when the size of the circular etching pattern is zero is calculated, and the etching time is used as the anti-corrosion time of the AlGaAs epitaxial layer.

2. The method for calibrating the corrosion resistance of a semiconductor epitaxial layer according to claim 1, characterized in that: The thickness of the AlGaAs epitaxial layer is in a range of greater than or equal to 2 nm and less than or equal to 20 nm.

3. The method for calibrating the corrosion resistance of a semiconductor epitaxial layer according to claim 2, characterized in that: The Al composition range of the AlGaAs epitaxial layer is greater than or equal to 0.1 and less than or equal to 0.

3.

4. The method for calibrating the corrosion resistance of a semiconductor epitaxial layer according to claim 1, characterized in that: In step b, the duration of each etching is in the range of greater than or equal to 1 min and less than or equal to 4 min.

5. The method for calibrating the corrosion resistance of a semiconductor epitaxial layer according to any one of claims 1 to 4, characterized in that: When observing with a microscope, the magnification of the microscope is 500 times or 1000 times.

6. The method for calibrating the corrosion resistance of a semiconductor epitaxial layer according to claim 1, characterized in that: In step b, after the circular corrosion pattern is observed under the microscope, the position of the circular corrosion pattern is marked, and the data of the size change of the marked circular corrosion pattern over the corrosion time is measured. If multiple circular corrosion patterns are observed under the microscope, the circular corrosion pattern with the largest size is selected for position marking.

Images