Method for forming germanium-silicon channel gate

Abstract

This invention provides a method for forming a germanium-silicon channel gate. The method includes providing a substrate, on which an oxide buried layer is formed, an insulating silicon layer is formed on the surface of the oxide buried layer, and a germanium-silicon layer is formed on the insulating silicon layer. The germanium-silicon layer is oxidized to form a first oxide layer on its upper surface. A second oxide layer is formed on the first oxide layer. Oxygen vacancy defects in the second oxide layer are repaired. This invention employs a low-pressure thermal oxidation method to form an ultrathin interface layer, followed by atomic oxide deposition to form a gate oxide of a certain thickness. Finally, a high-temperature plasma oxidation method is used to repair oxygen vacancy defects in the atomic oxide layer, thereby forming a high-quality gate oxide layer. This method yields a high-quality gate oxide layer and avoids the oxidation of germanium in the germanium-silicon channel, reducing interface defects and improving interface quality, thus enhancing device reliability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for forming a germanium-silicon channel gate. Background Technology

[0002] Compared to the traditional silicon-on-insulator (SOI) structure, the silicon-germanium-on-insulator (SGOI) structure can improve hole mobility and significantly enhance the performance of P-type metal oxide semiconductor field-effect transistors (PMOS).

[0003] Currently, the main method for forming germanium-silicon channel gates is through in-situ steam oxidation (ISSG). Existing methods use ISSG to form the interface layer, which oxidizes both silicon and germanium in the germanium-silicon channel to form silicon dioxide. This results in poor quality at the gate oxide interface, with numerous interface defects, severely impacting device reliability.

[0004] Therefore, a novel method for forming germanium-silicon channel gates is needed to form a high-quality gate oxide layer, avoid germanium oxidation in the germanium-silicon channel, reduce interface defects, improve interface quality, and thus improve device reliability. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for forming a germanium-silicon channel gate, which solves the problem that the existing method for forming a germanium-silicon channel gate mainly uses in-situ water vapor oxidation, but this will oxidize the silicon in the germanium-silicon channel to form silicon dioxide, and at the same time oxidize the germanium in the germanium-silicon channel to form germanium dioxide. This will result in poor quality at the gate oxide interface, more interface defects, and seriously affect the reliability of the device.

[0006] To achieve the above and other related objectives, the present invention provides a method for forming a germanium-silicon channel gate, comprising:

[0007] Step 1: Provide a substrate, on which an oxide buried layer is formed, an insulating silicon layer is formed on the surface of the oxide buried layer, and a germanium silicon layer is formed on the insulating silicon layer;

[0008] Step 2: Oxidize the germanium-silicon layer to form a first oxide layer on the upper surface of the germanium-silicon layer;

[0009] Step 3: Form a second oxide layer on the first oxide layer;

[0010] Step 4: Repair the oxygen vacancy defects in the second oxide layer.

[0011] Preferably, the substrate in step one is a silicon substrate.

[0012] Preferably, the first oxide layer is formed in step two using a low-pressure thermal oxidation method.

[0013] Preferably, the thickness of the first oxide layer in step two is 8 to 20 angstroms.

[0014] Preferably, in step two, the upper surface of the germanium-silicon layer is oxidized with oxygen or nitrous oxide.

[0015] Preferably, in the low-pressure thermal oxidation method described in step two, the temperature is 700 to 900 degrees Celsius, the oxygen introduction time is 10 to 60 seconds, and the pressure is 7 to 30 Torr.

[0016] Preferably, the material of the first oxide layer in step two is silicon dioxide.

[0017] Preferably, the material of the second oxide layer in step three is silicon dioxide.

[0018] Preferably, step three uses atomic vapor deposition to form the second oxide layer.

[0019] Preferably, in the atomic vapor deposition method of step three, the temperature is 200 to 380 degrees Celsius, and the cycle of the deposition machine is 15 to 50 times.

[0020] Preferably, the thickness of the second oxide layer in step three is 15 to 50 angstroms.

[0021] Preferably, in step four, a low-temperature plasma oxidation method is used to repair the oxygen vacancy defects in the second oxide layer.

[0022] Preferably, the low-temperature plasma oxidation in step four is carried out in a continuous operation mode, with a temperature of 150 to 450 degrees, a processing time of 8 seconds to 5 minutes, a pressure of 6 to 35 millitors, a radio frequency power of 150 to 500 watts, and an oxygen flow rate of 50 to 450 milliliters per minute.

[0023] As described above, the method for forming a germanium-silicon channel gate of the present invention has the following beneficial effects:

[0024] The germanium-silicon channel gate formation method provided by this invention replaces the traditional in-situ water vapor oxidation method with a three-step process of low-pressure thermal oxidation, atomic oxide deposition, and plasma oxidation. First, a low-pressure thermal oxidation method is used to form an ultrathin interface layer. Then, an atomic oxide deposition method is used to form a gate oxide of a certain thickness. Finally, a high-temperature plasma oxidation method is used to repair the oxygen vacancy defects in the atomic oxide layer, thereby forming a high-quality gate oxide layer. The gate oxide obtained by this method has high quality, and at the same time, it can avoid the oxidation of germanium in the germanium-silicon channel, reduce interface defects, improve interface quality, and thus improve the reliability of the device. Attached Figure Description

[0025] Figure 1 The diagram shown is a schematic representation of the process flow of the present invention.

[0026] Figure 2 The diagram shown is a schematic representation of the substrate of this invention.

[0027] Figure 3 The diagram shown illustrates the formation of the first oxide layer according to the present invention.

[0028] Figure 4 The diagram shown illustrates the formation of the second oxide layer according to the present invention.

[0029] Figure 5 The diagram shown illustrates the oxygen vacancy defect repair method of this invention. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] Please see Figure 1 The present invention provides a method for forming a germanium-silicon channel gate, comprising:

[0032] Step 1, please refer to Figure 2 A substrate 10 is provided, on which an oxide buried layer 11 is formed. Typically, the material of the oxide layer is silicon dioxide. An insulating silicon layer 12 is formed on the surface of the oxide buried layer 11, and a germanium silicon layer 13 is formed on the insulating silicon layer 12.

[0033] In one alternative embodiment, the substrate 10 in step one is a silicon substrate 10.

[0034] Step 2, please refer to Figure 3 Oxidize germanium-silicon layer 13, and oxidize the upper surface of germanium-silicon layer 13 to form first oxide layer 14;

[0035] In one alternative embodiment, the first oxide layer 14 is formed in step two using a low-pressure thermal oxidation method.

[0036] In one alternative embodiment, the thickness of the first oxide layer 14 in step two is 8 to 20 angstroms, preferably 8 angstroms. Since the first oxide layer 14 is thin, the oxidation of germanium can be avoided during the formation of the first oxide layer 14.

[0037] In an alternative embodiment, step two uses oxygen or nitrous oxide to oxidize the upper surface of the germanium silicon layer 13.

[0038] In one alternative embodiment, in the low-pressure thermal oxidation method of step two, the temperature is 700 to 900 degrees, the oxygen introduction time is 10 to 60 seconds, and the pressure is 7 to 30 Torr.

[0039] Specifically, a low-pressure thermal oxidation method can be used, in which oxygen or nitrous oxide gas is used to oxidize the upper surface of the germanium-silicon layer 13. The preferred temperature is 850 degrees Celsius, the preferred time is 19 seconds, and the preferred pressure is 12 Torr, which can prevent the oxidation of germanium.

[0040] In one alternative embodiment, the material of the first oxide layer 14 in step two is silicon dioxide.

[0041] Step 3, please refer to Figure 4 A second oxide layer 15 is formed on the first oxide layer 14;

[0042] In one alternative embodiment, the material of the second oxide layer 15 in step three is silicon dioxide.

[0043] In an alternative embodiment, step three involves forming a second oxide layer 15 using atomic vapor deposition.

[0044] In one alternative embodiment, in the atomic vapor deposition method of step three, the temperature is 200 to 380 degrees, the cycle of the deposition equipment is 15 to 50 times, and the precursor used for deposition is SAM24, which is a silicon-based compound and also a precursor material, also known as bis(diethylamino)silane.

[0045] In one alternative embodiment, the thickness of the second oxide layer 15 in step three is 15 to 50 angstroms, preferably 15 angstroms.

[0046] Step four, please refer to Figure 5 Oxygen vacancies are vacancies formed when oxygen atoms (oxygen ions) escape from the crystal lattice of metal oxides or other oxygen-containing compounds, resulting in oxygen loss. Simply put, they are defects left by oxygen ions escaping from the crystal lattice. Oxygen vacancies are one of the most common defects in semiconductor materials, especially metal oxide semiconductors, and have a significant impact on their performance. Therefore, it is necessary to repair the oxygen vacancy defects in the second oxide layer 15 to form a high-quality gate oxide layer.

[0047] In an alternative embodiment, in step four, a low-temperature plasma oxidation method is used to repair the oxygen vacancy defects in the second oxide layer 15.

[0048] In one alternative implementation, the low-temperature plasma oxidation in step four is carried out in a continuous operation mode, with a temperature of 150 to 450 degrees, a processing time of 8 seconds to 5 minutes, a pressure of 6 to 35 millitors, a radio frequency power of 150 to 500 watts for the plasma machine, and an oxygen flow rate of 50 to 450 ml per minute.

[0049] Specifically, the plasma oxidation temperature is preferably 30 degrees Celsius, the processing time is 50 seconds, the pressure is 15 mTorr, the plasma oxidation operation mode is continuous mode, the radio frequency power is 300 watts, and the oxygen flow rate is 500 ml per minute.

[0050] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0051] In summary, the germanium-silicon channel gate formation method provided by this invention replaces the traditional in-situ water vapor oxidation method with a three-step process: low-pressure thermal oxidation, atomic oxide deposition, and plasma oxidation. First, a low-pressure thermal oxidation method is used to form an ultrathin interface layer. Then, an atomic oxide deposition method is used to form a gate oxide of a certain thickness. Finally, a high-temperature plasma oxidation method is used to repair oxygen vacancy defects in the atomic oxide layer, thereby forming a high-quality gate oxide layer. This method yields high-quality gate oxide while avoiding germanium oxidation in the germanium-silicon channel, reducing interface defects, improving interface quality, and thus enhancing device reliability. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial applicability.

[0052] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for forming a germanium-silicon channel gate, characterized in that, At least including: Step 1: Provide a substrate, on which an oxide buried layer is formed, an insulating silicon layer is formed on the surface of the oxide buried layer, and a germanium silicon layer is formed on the insulating silicon layer; Step 2: The upper surface of the germanium-silicon layer is oxidized to form a first oxide layer using a low-pressure thermal oxidation method. In the low-pressure thermal oxidation method, the temperature is 700 to 900 degrees, the oxygen introduction time is 10 to 60 seconds, and the pressure is 7 to 30 Torr. The material of the first oxide layer is silicon dioxide. Step 3: Form a second oxide layer on the first oxide layer using atomic vapor deposition. Step 4: Repair the oxygen vacancy defects in the second oxide layer.

2. The method for forming a germanium-silicon channel gate according to claim 1, characterized in that: The substrate mentioned in step one is a silicon substrate.

3. The method for forming a germanium-silicon channel gate according to claim 1, characterized in that: The thickness of the first oxide layer in step two is 8 to 20 angstroms.

4. The method for forming a germanium-silicon channel gate according to claim 1, characterized in that: The material of the second oxide layer in step three is silicon dioxide.

5. The method for forming a germanium-silicon channel gate according to claim 1, characterized in that: In the atomic vapor deposition method described in step three, the temperature is 200 to 380 degrees Celsius, and the cycle time of the deposition equipment is 15 to 50 times.

6. The method for forming a germanium-silicon channel gate according to claim 1, characterized in that: The thickness of the second oxide layer in step three is 15 to 50 angstroms.

7. The method for forming a germanium-silicon channel gate according to claim 1, characterized in that: In step four, a low-temperature plasma oxidation method is used to repair the oxygen vacancy defects in the second oxide layer.

8. The method for forming a germanium-silicon channel gate according to claim 7, characterized in that: The low-temperature plasma oxidation described in step four adopts a continuous operation mode with a temperature of 150 to 450 degrees, a processing time of 8 seconds to 5 minutes, a pressure of 6 to 35 millitors, a radio frequency power of 150 to 500 watts, and an oxygen flow rate of 50 to 450 ml per minute.

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