A method for calibrating the corrosion resistance of a semiconductor epitaxial layer

Abstract

The present invention provides a method for calibrating the corrosion resistance of a semiconductor epitaxial layer, which relates to the technical field of semiconductor testing. The method includes: etching an InGaP epitaxial layer with an HCl etching solution; observing the surface of the sample with a microscope and measuring the data of the size of the circular etching pattern changing with the etching time; performing linear fitting on the data to obtain a linear function relationship; and calculating the etching time corresponding to the zero size of the pattern according to the linear function relationship. By measuring the relationship between the size of the etching pattern formed by the etching solution penetrating the AlGaAs epitaxial layer and the time, this method can calculate and infer the longest corrosion resistance time when the AlGaAs epitaxial layer is not penetrated, realizing the calibration of the corrosion resistance of the AlGaAs epitaxial layer, thereby providing a basis for the formulation of device processes.

Description

Technical Field

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

[0002] In a 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 corrosion process, usually, an HCl etching solution is used to selectively remove the InGaP material layer. Although the HCl etching solution has a high selectivity ratio for InGaP and AlGaAs, since the AlGaAs material layer contains Al elements, and the HCl etching solution is corrosive to Al, therefore, when the AlGaAs material layer is very thin, the etching time for removing the InGaP material layer with the HCl etching solution cannot be too long to avoid etching through the AlGaAs material layer.

[0003] Therefore, a method is needed 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 etching 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 to solve the problem of calibrating the corrosion resistance of the AlGaAs epitaxial layer in view of the deficiencies of the above-mentioned prior art.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a method for calibrating the corrosion resistance of a semiconductor epitaxial layer. This 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. The method includes:

[0007] Step a: Etch the second InGaP epitaxial layer with a pre-configured HCl etching solution, and the etching duration is less than or equal to a reference time period, where the reference time period is the expected time length for completely removing the second InGaP epitaxial layer with the HCl etching solution;

[0008] Step b: Alternately perform observing the surface of the sample with a microscope and etching the sample with the HCl etching solution. After observing a circular etching pattern in the microscope, measure the etching data of the size of the circular etching pattern changing with the etching time;

[0009] Step c: Perform linear fitting on the etching data to obtain a linear function relationship;

[0010] Step d: Calculate the corrosion time corresponding to the case where the size of the circular corrosion pattern is zero based on the linear function relationship, and use this corrosion time as the corrosion resistance time of the AlGaAs epitaxial layer.

[0011] Optionally, the thickness range of the AlGaAs epitaxial layer is greater than or equal to 2 nm and less than or equal to 20 nm.

[0012] Optionally, the Al composition range in the AlGaAs epitaxial layer is greater than or equal to 0.1 and less than or equal to 0.3.

[0013] Optionally, in step b, the duration of each corrosion ranges from greater than or equal to 1 min to less than or equal to 4 min.

[0014] Optionally, when observed with a microscope, the magnification of the microscope is 500 times or 1000 times.

[0015] Optionally, in step b, after observing the circular corrosion pattern in the microscope, mark the position of the circular corrosion pattern, and measure the corrosion data of the marked circular corrosion pattern changing with the corrosion time. If multiple circular corrosion patterns are observed in the microscope, select the circular corrosion pattern with the largest size for position marking.

[0016] The beneficial effects of the present invention include:

[0017] The method for calibrating the corrosion resistance of a semiconductor epitaxial layer provided by the present invention includes: Step a: Corrode the second InGaP epitaxial layer with a pre-configured HCl etching solution, and the corrosion duration is less than or equal to the reference time period, where the reference time period is the expected time length for completely removing the second InGaP epitaxial layer with the HCl etching solution; Step b: Alternately observe the sample surface with a microscope and corrode the sample with the HCl etching solution. After observing the circular corrosion pattern in the microscope, measure the corrosion data of the circular corrosion pattern changing with the corrosion time; Step c: Perform linear fitting on the corrosion data to obtain a linear function relationship; Step d: Calculate the corrosion time corresponding to the case where the size of the circular corrosion pattern is zero based on the linear function relationship, and use this corrosion time as the corrosion resistance time of the AlGaAs epitaxial layer. This method can calculate and infer the longest corrosion resistance time when the AlGaAs epitaxial layer is not penetrated by measuring the relationship between the size of the corrosion pattern formed by the etching solution penetrating the AlGaAs epitaxial layer and time, realizing the calibration of the corrosion resistance of the AlGaAs epitaxial layer, and thus providing a basis for the formulation of device processes. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 The flowchart of the method for calibrating the corrosion resistance of the semiconductor epitaxial layer provided by the embodiment of the present invention is shown;

[0020] Figure 2 The schematic diagram of the circular corrosion pattern provided by the embodiment of the present invention is shown;

[0021] Figure 3 The data graph showing the change of the corrosion pattern size with the corrosion time provided by the embodiment of the present invention is shown. Detailed implementation manners

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] In the GaAs-based pHEMT device structure, an AlGaAs material layer is usually used as the barrier layer, and an InGaP material layer on the AlGaAs material layer is used as the corrosion barrier layer. In the corrosion process, usually, an HCl etching solution is used to selectively remove the InGaP material layer. Although the HCl etching solution has a high selectivity ratio 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 using the HCl etching solution to etch and remove the InGaP material layer cannot be too long to avoid etching through the AlGaAs material layer.

[0024] Therefore, a method is needed 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.

[0025] As Figure 1 shown, the present invention provides a method for calibrating the corrosion resistance of a semiconductor epitaxial layer. This 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.

[0026] Optionally, the thickness of the AlGaAs epitaxial layer ranges from greater than or equal to 2 nm to less than or equal to 20 nm. Optionally, the Al composition in the AlGaAs epitaxial layer ranges from greater than or equal to 0.1 to less than or equal to 0.3.

[0027] The method includes:

[0028] Step a: Corrode the second InGaP epitaxial layer with a pre-configured HCl etching solution, and the etching duration is less than or equal to a reference time period, where the reference time period is the expected time length for completely removing the second InGaP epitaxial layer using the HCl etching solution.

[0029] Step b: Alternately perform observing the sample surface with a microscope and etching the sample with the HCl etching solution. After observing a circular etching pattern in the microscope, obtain etching data on the change in the size of the circular etching pattern with etching time.

[0030] Specifically, the surface of the sample after being etched in step a can be observed with a microscope, then the sample is continuously etched with the HCl etching solution, and then observed with a microscope again, and further etched until a circular etching pattern is observed in the microscope. After observing the circular etching pattern in the microscope, continue etching, and at regular intervals, observe and measure the size of the etching pattern (i.e., the diameter of the circular etching pattern) with a microscope, so that etching data on the change in the size of the circular etching pattern with etching time can be obtained.

[0031] 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 then penetrate the AlGaAs epitaxial layer. Before the HCl etching solution completely penetrates the AlGaAs epitaxial layer, the surface is observed to be flat and without etching marks in the microscope. When some points in the AlGaAs epitaxial layer are etched through, the HCl etching solution will reach the surface of the first InGaP epitaxial layer through the etching holes in the AlGaAs epitaxial layer, and thus continue to corrode the first InGaP epitaxial layer. At this time, a circular etching pattern will be observed in the microscope. As the etching time increases, the sizes of these circular etching patterns also increase. Within a certain time range, the relationship between the sizes of these etching patterns and the etching time changes approximately linearly. As Figure 2 shown, at Figure 2Among them, the circular figures are all the observed corrosion figures, which are the figures formed after the first InGaP epitaxial layer is corroded. For example, the solid circular line 20 is the corrosion figure observed after corroding for a certain period of time, and the dashed circular line 21 is the corrosion figure observed after further increasing the corrosion time. As the corrosion time increases, in addition to the increase in the size of the previous corrosion figures, new corrosion figures will also be observed.

[0032] Optionally, in step b, the duration of each corrosion ranges from greater than or equal to 1 min to less than or equal to 4 min. For example, 3 to 5 times of corrosion can be carried out. 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 figure in the microscope, mark the position of the circular corrosion figure, and measure the corrosion data of the marked circular corrosion figure changing with the corrosion time. If multiple circular corrosion figures are observed in the microscope, select the circular corrosion figure with the largest size for position marking. As Figure 2 shown, the mark 22 is only used to locate the position of the circular corrosion figure, so as to facilitate observing the change in the size of the figure at the same position during the next microscope observation. The mark 22 can be, for example, a scratch on the sample surface or other figures convenient for human eyes to identify. Although Figure 2 the mark 22 shown is a cross, it should be understood that the present application does not limit the specific shape of the mark 22.

[0033] Step c: Perform linear fitting on the corrosion data to obtain a linear function relationship.

[0034] Step d: According to the linear function relationship, calculate the corrosion time corresponding to when the size of the circular corrosion figure is zero, and use this corrosion time as the corrosion resistance time of the AlGaAs epitaxial layer.

[0035] As Figure 3 shown, by observing and measuring the size of the corrosion figure at the same point changing with the corrosion time through multiple microscope observations, measurement data ( Figure 3 the black square in) is formed. After linear fitting, a linear function relationship is obtained, and then the corrosion time t 0 corresponding to when the size of the circular corrosion figure is zero can be calculated. For Figure 3 the data in, the corrosion time t 0 can be used as the corrosion resistance time of the AlGaAs epitaxial layer.

[0036] By measuring the relationship between the size of the etching pattern formed by the etching solution penetrating the AlGaAs epitaxial layer and the change of time, the longest corrosion-resistant time of the unpenetrated AlGaAs epitaxial layer can be calculated and inferred, so as to realize the calibration of the corrosion resistance of the AlGaAs epitaxial layer, thereby providing a basis for the formulation of device processes.

[0037] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those of ordinary skill in the art to understand the content of the present invention and implement it. However, the protection scope of the present invention cannot be limited by this. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within 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-prepared 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 time length 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.

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