A method for manufacturing silicon germanium wafers.

Abstract

The objective is to provide a method for manufacturing silicon germanium wafers that allows for more accurate and faster control of the germanium concentration in silicon germanium. [Solution] The method for manufacturing a silicon germanium wafer comprises the steps of: depositing silicon germanium under multiple flow rate conditions by changing the germanium source gas flow rate; measuring the germanium concentration of the multiple deposited silicon germanium films; creating an approximation line representing the correlation between the multiple germanium source gas flow rates and the multiple germanium concentrations; determining the germanium source gas flow rate necessary to obtain a target germanium concentration using the approximation line; and depositing the silicon germanium film using the determined germanium source gas flow rate, wherein the germanium concentration of the silicon germanium film deposited for the creation of the approximation line is set to 3% or more and 50% or less.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a silicon germanium wafer. Background Art

[0002] In recent years, in addition to miniaturization, the adoption of dissimilar materials other than silicon has been progressing in semiconductor devices. For example, the applications cover a wide range: silicon germanium and germanium as high-mobility channel materials, silicon germanium as a sacrificial layer in gate-all-around structures and nanosheet structures, silicon carbide and gallium nitride as high-efficiency power device materials, etc. Particularly for silicon germanium, the germanium concentration varies widely depending on the application. Since it is necessary to adjust the germanium concentration in accordance with the intended use, there is a demand for a method for forming a film by quickly and accurately controlling the germanium concentration in silicon germanium.

[0003] In Patent Document 1, the flow rate of a germanium source gas is simply increased or decreased to increase or decrease the germanium concentration.

[0004] Patent Document 2 describes a characteristic diagram showing the relationship between the germane flow rate and the germanium composition ratio contained in a single-crystal silicon germanium layer in the growth of single-crystal SiGe using monosilane.

[0005] Patent Document 3 describes a graph plotting the film composition and deposition rate as a function of germane flow rate when using trisilane at 600°C with an H2 flow rate of 20 slm.

[0006] Although there are examples of the above-described techniques for increasing or decreasing the germanium concentration in silicon germanium and descriptions of characteristic diagrams, there is a need for a technique that defines the correlation between the germanium concentration and the flow rate of the germanium source gas as a clear procedure and method, and reliably forms a film of silicon germanium having a target germanium concentration. Prior Art Documents Patent Documents

[0007] [Patent Document 1] Patent No. 4696037 [Patent Document 2] Japanese Patent Publication No. 2004-193454 [Patent Document 3] Special Publication No. 2004-532511 [Overview of the project] [Problems that the invention aims to solve]

[0008] This invention has been made in view of the above circumstances, and aims to provide a method for manufacturing silicon germanium wafers that can control the germanium concentration of silicon germanium more accurately in a shorter amount of time. [Means for solving the problem]

[0009] The present invention has been made to achieve the above objective, and is a method for manufacturing a silicon germanium wafer, comprising the steps of: depositing silicon germanium at multiple flow rate conditions by changing the germanium source gas flow rate; measuring the germanium concentration of the multiple deposited silicon germanium films; creating an approximation line representing the correlation between the multiple germanium source gas flow rates and the multiple germanium concentrations; determining the germanium source gas flow rate necessary to obtain a target germanium concentration using the approximation line; and depositing the silicon germanium film using the determined germanium source gas flow rate, characterized in that the germanium concentration of the silicon germanium film deposited for the creation of the approximation line is 3% or more and 50% or less.

[0010] According to the present invention, as a method for manufacturing silicon germanium wafers, the germanium concentration of silicon germanium films deposited with two or more different germanium source gas flow rates is evaluated in advance, and the correlation between the gas flow rate and germanium concentration is determined. Under deposition conditions other than germanium source gas flow rate (temperature, pressure, silicon source gas flow rate), there is a linear relationship between germanium concentration and germanium source gas flow rate in the range of 3% to 50% germanium concentration. As a result, by calculating the germanium source gas flow rate required to obtain the desired germanium concentration from a linear approximation formula, the germanium concentration of the silicon germanium wafer can be controlled more accurately and in a shorter time.

[0011] In this case, the germanium concentration of the silicon germanium film deposited for the creation of the approximation line is set to 5% or more and 35% or less.

[0012] The germanium concentration in silicon germanium should ideally be around this level.

[0013] In this case, the germanium concentration of the silicon germanium film deposited for the creation of the approximation line is set to 10% or more and 30% or less.

[0014] This level of germanium concentration is more desirable for silicon germanium.

[0015] In this case, the germanium source gas flow rate when depositing the silicon germanium film for creating the approximation line is set to 20 sccm or more.

[0016] This prevents the germanium concentration in the deposited silicon germanium film from becoming too low.

[0017] In this case, the germanium source gas flow rate when depositing the silicon germanium film for creating the approximation line is set to 50 sccm or more.

[0018] This makes it possible to more reliably suppress the germanium concentration of the deposited silicon germanium from becoming excessively low.

[0019] In this case, when changing the flow rate of the germanium source gas for depositing the silicon germanium to create the approximate line, the range of change of the germanium source gas flow rate shall include a range where at least two flow rates have a difference of 1.5 times or more.

[0020] It is desirable that the change interval of the germanium source gas flow rate is of this degree.

[0021] In this case, when changing the flow rate of the germanium source gas for depositing the silicon germanium to create the approximate line, the range of change of the germanium source gas flow rate shall include a range where at least two flow rates have a difference of 2 times or more.

[0022] It is more desirable that the change interval of the germanium source gas flow rate is of this degree.

[0023] In this case, deposition conditions other than the flow rate of the germanium source gas when depositing the silicon germanium for creating the approximate line are set to the same conditions.

[0024] If deposition conditions other than the germanium source gas flow rate are changed, there is a possibility that errors included in the approximate line will increase. In other words, by setting deposition conditions other than the germanium source gas flow rate to the same conditions, errors included in the approximate line can be reduced, so a highly accurate approximate line can be obtained.

[0025] In this case, the germanium concentration of the silicon germanium deposited for creating the approximate line is measured using secondary ion mass spectrometry or X-ray diffraction.

[0026] As described above, the germanium concentration can be measured by destructive inspection or non-destructive inspection.

[0027] In this case, the approximation curve between the germanium source gas flow rate and the germanium concentration is linear.

[0028] If the approximation line is linear, it becomes easier to uniquely determine the required germanium source gas flow rate compared to the case of a curve.

[0029] In this case, the silicon germanium is deposited as an epitaxial film.

[0030] This invention can be used when forming a silicon germanium film as an epitaxial film.

[0031] In this case, at least one of GeH4, Ge2H6, and GeCl4 is used as the germanium source gas when depositing the silicon germanium film.

[0032] It is desirable to use at least one of GeH4, Ge2H6, or GeCl4 as the germanium source gas.

[0033] In this case, at least one of SiH4, SiH2Cl2, SiHCl3, Si2H6, and SiCl4 is used as the silicon source gas when forming the silicon germanium film.

[0034] It is desirable to use at least one of the following silicon source gases: SiH4, SiH2Cl2, SiHCl3, Si2H6, and SiCl4. [Effects of the Invention]

[0035] As described above, the silicon germanium wafer manufacturing method of the present invention allows for more accurate and faster control of the germanium concentration in the silicon germanium. [Brief explanation of the drawing]

[0036] [Figure 1]This graph shows the correlation between GeH4 flow rate and germanium concentration under various film deposition conditions for the silicon germanium wafer of the present invention. [Modes for carrying out the invention]

[0037] Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto. As an example of a method for manufacturing a silicon germanium wafer, steps 1 to 5 will be described.

[0038] (1st step) In the first step, silicon germanium is deposited under multiple flow rate conditions by changing the germanium source gas flow rate. For example, if there are six germanium source gas flow rate conditions, six types of silicon germanium films will be deposited. To create an approximation line in the third step described later, it is preferable that the germanium source gas flow rate when depositing silicon germanium is 20 sccm or more. More preferably, it is preferable that the germanium source gas flow rate when depositing silicon germanium is 50 sccm or more.

[0039] When changing the germanium source gas flow rate during silicon germanium film deposition in order to create the approximation line described later, it is preferable that the range of change in germanium source gas flow rate includes a range where at least two flow rates differ by 1.5 times or more. For example, if the germanium source gas flow rate within the change range includes flow rate A and flow rate B, and flow rate B is greater than flow rate A, it is preferable that the flow rate ratio B / A is 1.5 or greater. More preferably, for two flow rates (flow rate A and flow rate B), the flow rate ratio B / A is 2 or more. Note that within the range of germanium source gas flow rate adjustment, the number of selectable flow rates is not limited to two; there may be three or more. Thus, it is preferable that the range of germanium source gas flow rate adjustment includes a range where at least two flow rates differ by a factor of two or more.

[0040] (2nd process) In the second step, the germanium concentration of the multiple silicon germanium films deposited in the first step is measured. In other words, the germanium concentration of the silicon germanium films deposited is measured in order to create the approximation line described later. The germanium concentration in silicon germanium can be measured using secondary ion mass spectrometry or X-ray diffraction.

[0041] Secondary ion mass spectrometry is a method for measuring the types and concentrations of elements contained in a sample by irradiating the sample surface with primary ions in a vacuum and then performing mass analysis on the secondary ions emitted from the sample.

[0042] X-ray diffraction is a method in which the diffraction intensity of a known substance and the component to be detected are measured, and the germanium concentration is determined using the lattice constants of these substances to create a calibration curve. Then, the concentration of the component to be detected is determined using this calibration curve.

[0043] (3rd step) In the third step, an approximation line is created that represents the correlation between multiple germanium source gas flow rates and multiple germanium concentrations. Specifically, an approximation line representing the correlation is created using the multiple germanium source gas flow rates selected in the first step and the multiple germanium concentrations in the multiple silicon germanium films deposited in the second step at the flow rates of the first step. For example, a graph with multiple plots is obtained by plotting germanium source gas flow rates on the horizontal axis and germanium concentrations on the vertical axis. Then, an approximation line is created by finding an approximation formula for the multiple plots.

[0044] The germanium concentration of the silicon germanium film deposited for creating the approximation line shall be between 3% and 50%. Preferably, the germanium concentration shall be between 5% and 35%. More preferably, the germanium concentration shall be between 10% and 30%. The appropriate range of germanium concentration will be shown in the examples described later. For creating an approximation line, it is preferable to keep the deposition conditions the same except for the germanium source gas flow rate when depositing silicon germanium.

[0045] It is preferable that the approximation curve between the germanium source gas flow rate and germanium concentration is linear.

[0046] (4th step) In the fourth step, the germanium source gas flow rate required to obtain the target germanium concentration is determined using the approximation line obtained in the third step. Specifically, the target germanium concentration is substituted into the approximation formula obtained in the third step to determine the germanium source gas flow rate. The determined flow rate is then determined as the germanium source gas flow rate under the film deposition conditions.

[0047] (5th step) In the fifth step, silicon germanium is deposited using the germanium source gas flow rate determined in the fourth step as one of the deposition conditions. In this case, it is preferable that the silicon germanium is deposited as an epitaxial film.

[0048] When depositing a silicon germanium film, it is preferable to use at least one of GeH4, Ge2H6, and GeCl4 as the germanium source gas.

[0049] When forming a silicon germanium film, it is preferable to use at least one of SiH4, SiH2Cl2, SiHCl3, Si2H6, and SiCl4 as the silicon source gas.

[0050] The manufacturing method for silicon germanium wafers involves performing the above steps 1 through 5. Since an approximate formula for the relationship between germanium concentration and germanium source gas flow rate has been determined in advance, the germanium concentration of the silicon germanium can be controlled more accurately and in a shorter time. [Examples]

[0051] The present invention will be further described below based on examples, but these examples are illustrative and should not be interpreted as limiting.

[0052] (Example 1) Under condition 3 shown in Figure 1, with the temperature (650°C), pressure (1333 Pa), and silicon source gas flow rate (600 sccm) kept constant, the GeH4 gas flow rate was varied within the range of 25 to 350 sccm, and silicon germanium was epitaxially grown on a 300 mm diameter silicon wafer. When the germanium concentration of this epitaxial wafer was measured using secondary ion mass spectrometry, the germanium concentration varied within the range of 3 to 27%. Furthermore, a proportional relationship was observed between the GeH4 gas flow rate and the germanium concentration.

[0053] (Example 2) As shown in Figure 1, Condition 2 involved using different values ​​for temperature, pressure, and silicon source gas flow rate than Condition 3. Specifically, the temperature was set to 650°C, the pressure to 1333 Pa, and the silicon source gas flow rate to 200 sccm. Here, the GeH4 gas flow rate was varied in the range of 25 to 350 sccm, and silicon germanium was epitaxially grown on a silicon wafer with a diameter of 300 mm. When the germanium concentration of this epitaxial wafer was measured using secondary ion mass spectrometry, the germanium concentration varied in the range of 7 to 41%. Furthermore, a proportional relationship was observed between the GeH4 gas flow rate and the germanium concentration.

[0054] (Example 3) As shown in Figure 1, under condition 1, the temperature, pressure, and silicon source gas flow rate were set to different values ​​from those of conditions 2 and 3. Specifically, the temperature was set to 600°C, the pressure to 1333 Pa, and the silicon source gas flow rate to 200 sccm. Here, the GeH4 gas flow rate was varied in the range of 25 to 300 sccm, and silicon germanium was epitaxially grown on a silicon wafer with a diameter of 300 mm. When the germanium concentration of this epitaxial wafer was measured using secondary ion mass spectrometry, the germanium concentration varied in the range of 17 to 50%. A proportional relationship was observed between the GeH4 gas flow rate and the germanium concentration in the range of 25 to 300 sccm.

[0055] (Comparative Example 1) Under Condition 1, with temperature, pressure, and silicon source gas flow rate kept constant, and the GeH4 gas flow rate set to 350 sccm, silicon germanium was epitaxially grown on a silicon wafer with a diameter of 300 mm. When the germanium concentration of this epitaxial wafer was measured using secondary ion mass spectrometry, the germanium concentration was found to be 52%, which deviated from the proportional relationship observed in Example 3.

[0056] Figure 1 shows Examples 1, 2, and 3, and Comparative Example 1 together. In Figure 1, the line representing the approximation formula for Condition 1 is shown as calibration curve K1, the line representing the approximation formula for Condition 2 is shown as calibration curve K2, and the line representing the approximation formula for Condition 3 is shown as calibration curve K3. In Figure 1, a proportional relationship was observed between the GeH4 gas flow rate and germanium concentration in the range of 3% to 50% for the germanium concentration of silicon germanium.

[0057] Therefore, by pre-depositing silicon germanium epitaxial wafers with two or more different germanium source gas flow rates, evaluating the germanium concentration for each germanium source gas flow rate, plotting these two conditions on a correlation diagram between germanium source gas flow rate and germanium concentration, and creating approximation curves (calibration curves K1, K2, K3), it becomes possible to reliably deposit silicon germanium with the desired germanium concentration.

[0058] However, the germanium concentration in at least two of the above conditions must be in the range of 3% to 50%. Furthermore, in order to obtain a highly accurate approximation line, the germanium source gas flow rate must be 20 sccm or more, and there must be a difference of 1.5 times or more in flow rate between the two conditions. For example, by making the difference between the maximum and minimum flow rates as large as possible, the error in the slope of the approximation line is reduced, thus improving the accuracy of the approximation line.

[0059] This specification includes the following embodiments: [1]: A method for manufacturing a silicon germanium wafer, comprising the steps of: depositing silicon germanium at multiple flow rate conditions by changing the germanium source gas flow rate; measuring the germanium concentration of the multiple deposited silicon germanium films; creating an approximation line representing the correlation between the multiple germanium source gas flow rates and the multiple germanium concentrations; determining the germanium source gas flow rate necessary to obtain a target germanium concentration using the approximation line; and depositing the silicon germanium film using the determined germanium source gas flow rate, wherein the germanium concentration of the silicon germanium film deposited for the creation of the approximation line is 3% or more and 50% or less. [2]: A method for manufacturing a silicon germanium wafer according to [1], wherein the germanium concentration of the silicon germanium film deposited for the creation of the approximation line is 5% or more and 35% or less. [3]: A method for manufacturing a silicon germanium wafer according to [1], wherein the germanium concentration of the silicon germanium film deposited for creating the approximation line is 10% or more and 30% or less. [4]: A method for manufacturing a silicon germanium wafer according to [1], [2], or [3], wherein the germanium source gas flow rate when depositing the silicon germanium film for creating the approximate line is 20 sccm or more. [5]: A method for manufacturing a silicon germanium wafer according to [1], [2], or [3], wherein the germanium source gas flow rate when depositing the silicon germanium for creating the approximate line is 50 sccm or more. [6]: The method for manufacturing a silicon germanium wafer according to [1], [2], or [3] above, wherein when the germanium source gas flow rate is changed when depositing the silicon germanium to create the approximate line, the range of change of the germanium source gas flow rate includes a range in which there is a difference of 1.5 times or more between at least two flow rates. [7]: The method for manufacturing a silicon germanium wafer according to [1], [2], or [3] above, wherein when the germanium source gas flow rate is changed when depositing the silicon germanium to create the approximate line, the range of change of the germanium source gas flow rate includes a range in which there is a difference of more than two times between at least two flow rates. [8]: A method for manufacturing a silicon germanium wafer according to [1], [2], [3], [4], [5], [6], or [7] above, wherein the film deposition conditions other than the germanium source gas flow rate when depositing the silicon germanium for creating the approximate line are the same. [9]: A method for manufacturing a silicon germanium wafer according to [1], [2], [3], [4], [5], [6], [7], or [8], wherein the germanium concentration of the silicon germanium film deposited for the creation of the approximation line is measured by secondary ion mass spectrometry or X-ray diffraction.

[10] : A method for manufacturing a silicon germanium wafer according to [1], [2], [3], [4], [5], [6], [7], [8] or [9] above, wherein the approximate line of the germanium source gas flow rate and the germanium concentration is linear.

[11] : A method for manufacturing a silicon germanium wafer according to [1], [2], [3], [4], [5], [6], [7], [8], [9] or

[10] , wherein the silicon germanium is formed as an epitaxial film.

[12] : A method for manufacturing a silicon germanium wafer according to [1], [2], [3], [4], [5], [6], [7], [8], [9],

[10] , or

[11] , wherein at least one of GeH4, Ge2H6, and GeCl4 is used as the germanium source gas when forming the silicon germanium film.

[13] : A method for manufacturing a silicon germanium wafer according to [1], [2], [3], [4], [5], [6], [7], [8], [9],

[10] ,

[11] , or

[12] above, using at least one of SiH4, SiH2Cl2, SiHCl3, Si2H6, and SiCl4 as the silicon source gas when forming the silicon germanium film.

[0060] It should be noted that the present invention is not limited to the embodiments (examples) described above. The embodiments described above are illustrative, and any configuration that has substantially the same technical idea as described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. A method for manufacturing silicon germanium wafers, A process of depositing silicon germanium films under multiple flow rate conditions by changing the germanium source gas flow rate, A step of measuring the germanium concentration of multiple silicon germanium films that have been deposited, A step of creating an approximation line representing the correlation between multiple germanium source gas flow rates and multiple germanium concentrations, A step of determining the germanium source gas flow rate necessary to obtain the target germanium concentration using the aforementioned approximation line, The process consists of a step of forming a silicon germanium film using the determined germanium source gas flow rate, A method for manufacturing a silicon germanium wafer, characterized in that the germanium concentration of the silicon germanium film deposited for the creation of the aforementioned approximation line is 3% or more and 50% or less.

2. The method for manufacturing a silicon germanium wafer according to claim 1, characterized in that the germanium concentration of the silicon germanium film deposited for the creation of the aforementioned approximation line is 5% or more and 35% or less.

3. The method for manufacturing a silicon germanium wafer according to claim 1, characterized in that the germanium concentration of the silicon germanium film deposited for the creation of the aforementioned approximation line is 10% or more and 30% or less.

4. A method for manufacturing a silicon germanium wafer according to any one of claims 1 to 3, characterized in that the germanium source gas flow rate when depositing the silicon germanium film for creating the aforementioned approximation line is 20 sccm or more.

5. A method for manufacturing a silicon germanium wafer according to any one of claims 1 to 3, characterized in that the germanium source gas flow rate when depositing the silicon germanium film for creating the aforementioned approximation line is 50 sccm or more.

6. The method for manufacturing a silicon germanium wafer according to any one of claims 1 to 3, characterized in that when the germanium source gas flow rate is changed when depositing the silicon germanium film in order to create the aforementioned approximation line, the range of change in the germanium source gas flow rate includes a range in which there is a difference of 1.5 times or more between at least two flow rates.

7. The method for manufacturing a silicon germanium wafer according to any one of claims 1 to 3, characterized in that when the germanium source gas flow rate is changed when depositing the silicon germanium film in order to create the aforementioned approximation line, the range of change in the germanium source gas flow rate includes a range in which there is a difference of at least two times between the flow rates.

8. A method for manufacturing a silicon germanium wafer according to any one of claims 1 to 3, characterized in that the film deposition conditions other than the germanium source gas flow rate when depositing the silicon germanium film for creating the aforementioned approximation line are the same.

9. A method for manufacturing a silicon germanium wafer according to any one of claims 1 to 3, characterized in that the germanium concentration of the silicon germanium film deposited for the creation of the aforementioned approximation line is measured using secondary ion mass spectrometry or X-ray diffraction.

10. A method for manufacturing a silicon germanium wafer according to any one of claims 1 to 3, characterized in that the approximation line between the germanium source gas flow rate and the germanium concentration is linear.

11. A method for manufacturing a silicon germanium wafer according to any one of claims 1 to 3, characterized in that the silicon germanium is formed as an epitaxial film.

12. As the germanium source gas when depositing the silicon germanium film, GeH ４ , Ge ２ H ６ GeCl ４ A method for manufacturing a silicon germanium wafer according to any one of claims 1 to 3, characterized by using at least one of the following.

13. As a silicon source gas for forming the silicon germanium film, SiH ４ , SiH ２ Cl ２ , SiHCl ３ , Si ２ H ６ , SiCl ４ The method for producing a silicon germanium wafer according to any one of claims 1 to 3, wherein at least one or more of the foregoing is used.

Images