KR101152441B1 - Method for forming dielectric layer on Ge-based semiconductor layer and method for fabricating semiconductor device using the same - Google Patents

Abstract

A method of forming a dielectric film on a Ge-based semiconductor layer and a method of manufacturing a semiconductor device using the same are provided. After loading a substrate having a Ge-based semiconductor layer on which a Ge oxide layer is formed into a deposition apparatus, H ₂ O vapor is supplied onto the substrate to etch the Ge oxide layer. After the substrate is heated and stabilized in the H ₂ O vapor supply step, a dielectric film is deposited without vacuum breaking. The substrate on which the dielectric film is deposited is unloaded from the deposition apparatus. As such, the Ge oxide film having poor quality can be easily etched through the H ₂ O vapor supply step to improve the dielectric film reliability, and also by simultaneously performing the H ₂ O vapor supply step and the stabilization step for the dielectric film deposition. The dielectric film deposition rate can be improved.

Description

Method for forming dielectric layer on Ge-based semiconductor layer and method for fabricating semiconductor device using the same}

The present invention relates to a method of forming a dielectric film, and more particularly, to a method of forming a dielectric film on a Ge-based semiconductor layer.

Recently, due to the rapid development of information and communication technology, a new concept of electronic device structure or material that can exhibit increased operation speed at low voltage is required. In fact, it has long been known that Ge layers exhibit greater electron and hole mobility than Si layers. However, since it is difficult to form a reliable oxide film on the Ge layer, the technique of forming an element using the Si layer rather than the Ge layer has been commercialized.

However, as described above, the development of information and communication technology requires a high speed device, and accordingly, the demand for development of a Ge semiconductor device is increasing. Therefore, in order to manufacture a reliable Ge semiconductor element, forming a reliable oxide film on the Ge layer has become a prerequisite problem.

An object of the present invention is to provide a method of forming a reliable dielectric film on a Ge-based semiconductor layer, and an electronic device manufacturing method using the same.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above technical problem, an aspect of the present invention provides a method for forming a dielectric film. First, a substrate having a Ge-based semiconductor layer is provided. The substrate is loaded into the deposition apparatus. After heating the substrate while supplying H ₂ O vapor on the substrate, a dielectric film is deposited without breaking the vacuum. The substrate on which the dielectric film is deposited is unloaded from the deposition apparatus.

In addition to the H ₂ O vapor, an inert gas may be supplied onto the substrate.

The step of supplying H ₂ O vapor on the substrate and depositing the dielectric film may be performed in-situ in the same chamber of the deposition apparatus. Alternatively, supplying H ₂ O vapor onto the substrate and depositing the dielectric film may be performed without vacuum breakdown in different chambers of the deposition apparatus.

The dielectric layer may be an oxide layer.

Before loading the substrate into the deposition apparatus, the HF aqueous solution washing and the deionized water washing may be repeatedly performed on the substrate.

In order to achieve the above technical problem, an aspect of the present invention provides another method of forming a dielectric film. First, a substrate including a Ge-based semiconductor layer and a Ge oxide film formed on the Ge-based semiconductor layer is provided. The substrate is loaded into the deposition apparatus. H ₂ O vapor is supplied onto the substrate to etch the Ge oxide film and to deposit a dielectric film without vacuum breaking. The substrate on which the dielectric film is deposited is unloaded from the deposition apparatus. The substrate may be heated to the dielectric film deposition temperature while supplying H ₂ O vapor on the substrate.

Another aspect of the present invention to achieve the above technical problem provides a method of manufacturing a semiconductor device. First, a substrate having a Ge-based semiconductor layer is provided. The substrate is loaded into the deposition apparatus. After heating the substrate while supplying H ₂ O vapor on the substrate, a dielectric film is deposited without breaking the vacuum. The substrate on which the dielectric film is deposited is unloaded from the deposition apparatus. A conductive film is formed on the dielectric film.

As described above, according to the present invention, the Ge oxide film having a low density and permittivity and having a plurality of interfacial trap sites can be effectively etched through the H ₂ O vapor supply step. This can improve the reliability of the dielectric film, and can also improve the reliability of the semiconductor device including the dielectric film.

In addition, by performing the H ₂ O vapor supply step and the dielectric film deposition step without vacuum breakdown in the same deposition apparatus, by etching the Ge oxide layer in the H ₂ O vapor supply step so that the substrate is not in contact with the oxygen atmosphere The formation of additional Ge oxide layers can be prevented. In addition, since the substrate surface is terminated through the H ₂ O vapor supply step, the deposition rate of the dielectric layer, in particular, the oxide layer, may be increased later. In addition, by heating the substrate to the dielectric film deposition temperature in the H ₂ O vapor supply step, the additional stabilization step may not be performed in the dielectric film deposition step, the deposition rate of the dielectric film, in particular, the oxide film may be faster.

1 is a flowchart illustrating a method of forming a dielectric film according to an embodiment of the present invention. 2A to 2D are cross-sectional views illustrating a method of forming a dielectric film according to an embodiment of the present invention.
3A and 3B are cross-sectional views illustrating a method of manufacturing a semiconductor device in accordance with another embodiment of the present invention.
4 is a graph showing the removal thickness of the Ge oxide film according to the H ₂ O vapor supply time.
5 is a graph showing the HfO ₂ thickness according to the H ₂ O steam supply time.
6 is a graph showing capacitance according to electrode voltages of MOS capacitors according to Preparation Example 1 and Comparative Example 1. FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to describe the present invention in more detail. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. In the figures, where a layer is said to be "on" another layer or substrate, it may be formed directly on the other layer or substrate, or a third layer may be interposed therebetween.

1 is a flowchart illustrating a method of forming a dielectric film according to an embodiment of the present invention. 2A to 2D are cross-sectional views illustrating a method of forming a dielectric film according to an embodiment of the present invention.

Referring to FIG. 2A, a Ge based semiconductor layer 110 is provided. The Ge-based semiconductor layer 110 is a semiconductor layer containing Ge, and may be, for example, a Ge layer or a SiGe layer. In addition, the Ge-based semiconductor layer 110 may be a single crystal layer, a polycrystalline layer, or an amorphous layer.

The Ge-based semiconductor layer 110 may be a Ge-based substrate. In contrast, the Ge-based semiconductor layer 110 is a layer formed on another substrate, for example, a Ge on Silicon (GOS) layer formed on a Si substrate, or a Ge on insulator (GOI) or a SiGe on insulator (SGOI). It may be a layer formed on an insulator such as.

The Ge oxide layer 120 is formed on the Ge-based semiconductor layer 110. The Ge oxide layer 120 may be a natural oxide film. The Ge oxide layer 120 has a low density and dielectric constant and may have a plurality of interfacial trap sites.

1 and 2B, the substrate including the Ge-based semiconductor layer 110 and the Ge oxide layer 120 is cleaned (S10), and the Ge oxide layer 120 is etched. At this time, HF aqueous solution can be used as a washing | cleaning agent. In addition, washing with deionized water may be further performed. Since the Ge oxide layer 120 is known to be water soluble, the Ge oxide layer 120 may be etched by washing with HF aqueous solution and / or deionized water.

As an example, the HF aqueous solution washing and the deionized water washing may be repeatedly performed several times. Since the Ge-based semiconductor layer 110 may be easily dissolved in HF, and the cleaning using the HF aqueous solution is performed for a long time, the surface flatness of the Ge-based semiconductor layer 110 may be deteriorated. The HF aqueous solution washing time may be adjusted so as not to deteriorate the surface flatness of the (110), and it is preferable to repeatedly perform the HF aqueous solution washing and the deionized water washing several times.

The substrate cleaning step S10 may be performed in a chemical bath. After the substrate cleaning step S10 is completed, subsequent steps may be performed while the substrate is not exposed to air to prevent oxidation.

The Ge oxide layer 120 may remain on the substrate that has undergone the substrate cleaning step S10.

1 and 2C, the cleaned substrate is loaded into the dielectric film deposition apparatus (S20). Thereafter, the remaining gas in the deposition apparatus may be pumped to lower the pressure inside the deposition apparatus to 10 torr or less to be almost vacuum. This can be done using a vacuum pump connected to the deposition apparatus.

Thereafter, H ₂ O vapor is supplied to the substrate in the deposition apparatus (S30). At this time, the substrate may be stabilized by heating to the dielectric film deposition temperature in the subsequent dielectric film deposition step. In addition to the H ₂ O vapor, an inert gas such as He, Ar, or N ₂ may be supplied onto the substrate. The H ₂ O vapor provided on the substrate may etch the Ge oxide layer 120 to reduce the thickness of the Ge oxide layer 120. It is also possible to provide OH groups on the substrate surface. In this case, since the H ₂ O vapor may be provided at a low pressure so that the Ge oxide layer 110 may not be etched rapidly, the surface flatness of the Ge oxide layer 110 may not be degraded.

All of the Ge oxide layer 120 may be etched on the substrate after the H ₂ O vapor supply step (S30), or some may remain.

1 and 2D, a dielectric film 130 is deposited on a substrate on which the Ge oxide film 120 is etched by H ₂ O steam treatment (S40). The H ₂ O vapor supply step (S30) and the dielectric film deposition step (S40) may be performed in the same deposition apparatus without vacuum break (vacuum break).

The deposition apparatus may be a device having a single chamber or a device having multiple chambers. When the deposition apparatus is a device having a single chamber, the H ₂ O vapor supply step S30 and the dielectric film deposition step S40 may be performed in-situ in the same chamber. When the deposition apparatus is a device having a multi-chamber, the H ₂ O vapor supply step (S30) and the dielectric film deposition step (S40) is in-situ in any one of the plurality of chambers ) Or each in two of the plurality of chambers without vacuum breakdown.

As such, by performing the H ₂ O vapor supply step (S30) and the dielectric film deposition step (S40) without vacuum breaking in the same deposition apparatus, the Ge oxide layer 120 in the H ₂ O vapor supply step (S30). After etching), the substrate may not be in contact with the oxygen atmosphere to prevent the formation of additional Ge oxide layers. In addition, since the substrate surface is terminated by the OH group through the H ₂ O vapor supply step (S30), the deposition rate of the dielectric layer, in particular, the oxide layer may be increased later. In addition, by heating the substrate to the dielectric film deposition temperature in the H ₂ O vapor supply step (S30), the additional stabilization step may not be performed in the dielectric film deposition step (S40) to increase the deposition rate of the dielectric film, in particular, the oxide film Can be.

The dielectric layer 130 may be an oxide layer, for example, SiO ₂ , Al ₂ O ₃ , HfO ₂ , ZrO ₂ , Y ₂ O ₃ , V ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , SrTiO ₃ , BaTiO ₃ , BaSrTiO ₃ , PbTiO ₃ , ZrTiO ₃ , PbZrTiO ₃ , or a nitride film such as Si ₃ N ₄ . Alternatively, the dielectric layer 130 may be formed of multiple layers of different types of oxide layers, or multiple layers of oxide and nitride layers, for example, SiO ₂ / Si ₃ N ₄ , HfO ₂ / Al ₂ O ₃ , ZrO ₂ / Al ₂ O ₃ , HfO ₂ / Ta ₂ O ₅ , Al ₂ O ₃ / HfO ₂ / Al ₂ O ₃ . When the dielectric film 130 is a multilayer of an oxide film and a nitride film, it is preferable to form an oxide film first. This is because the oxide film can be quickly deposited by the surface of the substrate finished with OH through the H ₂ O vapor supply step (S30). The dielectric layer 130 may be a high dielectric layer. The specific conductive layer can reduce the leakage current passing through the dielectric layer 130, high dielectric constant as compared to SiO _2, from thicker than the SiO ₂ can represent the same equivalent oxide thickness (EOT) and SiO _2.

The dielectric layer 130 may be formed using a chemical vapor deposition (CVD) method or an atomic layer deposition (ALD) method. As an example, the dielectric film 130 which is an oxide film may be formed by the reaction of the metal precursor and the oxidant, or the dielectric film 130 which is the nitride film may be formed by the reaction of the metal precursor and the nitriding agent. The metal precursor may be a metal halide, metal alkoxide, or metal amine, the oxidant may be H ₂ O, H ₂ O ₂ , O ₃ , O ₂ plasma, alcohol, or alkoxymethyl, and the nitriding agent may be NH 3, N ₂ plasma may be. In one example, the oxidant may be H ₂ O. In one embodiment, when the dielectric film 130 is HfO ₂ and is formed using the ALD method, the metal precursor may be Hf [NCH ₃ C ₂ H ₅ ] ₄ and the oxidant may be H ₂ O gas.

Thereafter, the substrate 100 on which the dielectric film 130 is deposited is unloaded from the deposition apparatus (S50).

3A and 3B are cross-sectional views illustrating a method of manufacturing a semiconductor device in accordance with another embodiment of the present invention.

Referring to FIG. 3A, a conductive film 140 is formed on the dielectric film 130 formed using the method described with reference to FIGS. 2A to 2D. The conductive layer 140 may be polysilicon, metal nitride, or metal layer. As an example, the conductive layer 140 may be polysilicon, TiN, TaN, WN, W, Pt, Ir, or a composite film thereof.

As such, the Ge-based semiconductor film 110, the dielectric film 130, and the conductive film 140 may form a MOS capacitor. At this time, the Ge oxide film 120 may remain between the semiconductor film 110 and the dielectric film 130. However, as described with reference to FIGS. 2A through 2D, the Ge oxide film 120 may be H ₂ O. As the dielectric layer 130 is formed without etching under vacuum after etching using steam, the thickness of the relatively defective Ge oxide layer 120 may be reduced. As a result, the reliability of the capacitor can be improved and the capacitance can also be improved.

Referring to FIG. 3B, the conductive layer 140 and the dielectric layer 130 are further patterned to form a gate electrode G and expose the Ge-based semiconductor layer 110 around the gate electrode G. Referring to FIG. An impurity may be injected into the exposed Ge-based semiconductor layer 110 to form a source region S and a drain region D to form a MOS transistor.

In the MOS transistor, as described above, the Ge oxide layer 120 may remain between the Ge-based semiconductor layer 110 and the dielectric layer 130. However, the MOS transistor may be formed by reducing the thickness of the Ge oxide layer 120. It is possible to improve the reliability of the transistor and to improve the transistor operating speed due to the increased capacitance.

Hereinafter, preferred examples are provided to aid the understanding of the present invention. However, the following experimental examples are only for helping understanding of the present invention, and the present invention is not limited to the following experimental examples.

Experimental Examples; examples>

Experimental Example 1

Impurities, such as an organic substance on the prepared Ge substrate, were removed. Subsequently, a Ge substrate was loaded into the reactor, and O ₂ was supplied at 500 ° C. for 30 minutes into the reactor to artificially form a 70 nm Ge oxide film on the Ge substrate. Thereafter, the substrate on which the Ge oxide film was formed was loaded into an ALD chamber, and the substrate was heated to 350 ° C. to supply H ₂ O vapor into the chamber to etch the Ge oxide film.

Subsequently, Hf [NCH ₃ C ₂ H ₅ ] ₄ as a metal oxide precursor, a first purge step, and H ₂ O vapor as an oxidizing agent were supplied at 350 ° C. on a substrate on which the Ge oxide film was etched by H ₂ O steam treatment. The cycle consisting of the step and the second purge step was repeated 40 times to form an HfO ₂ film.

4 is a graph showing the removal thickness of the Ge oxide film according to the H ₂ O vapor supply time.

Referring to FIG. 4, it can be seen that first, the Ge oxide film may be etched by performing H ₂ O vapor treatment in an ALD deposition apparatus. In addition, the Ge oxide film was rapidly etched to 8.4 mW / min until the H ₂ O vapor supply time was 120 seconds, but decreased to 1.9 mW / min after 120 seconds. This can be seen as a result of the gradually decreasing volume of Ge oxide remaining on the substrate.

5 is a graph showing the HfO ₂ thickness according to the H ₂ O steam supply time.

Case 5, that even though carried out in the same manner for 40 cycles and the supply H ₂ O vapor, if not supplied (H ₂ O vapor if the supply time is 0), H ₂ O vapor as compared to the HfO2 Deposition thickness increased. This is because the surface of the Ge oxide film is changed to hydrophilic by OH group by H ₂ O vapor supply, the incubation cycle (HfO 2) is reduced to improve the HfO 2 deposition rate.

Although 40 cycles were performed identically, the deposition thickness of HfO ₂ increased rapidly until the H ₂ O vapor supply time was 120 seconds. However, when the H ₂ O vapor supply time exceeds 120 seconds, the increase in HfO 2 deposition thickness tends to be alleviated, presumably because the surface is sufficiently hydrophilic as the vapor supply time passes over 120 seconds.

<MOS capacitor manufacturing example 1>

Impurities, such as an organic substance on the prepared Ge substrate, were removed. Subsequently, the second step of washing for 10 seconds using an aqueous HF solution and 20 seconds of washing with deionized water was repeated five times to etch the Ge oxide film as a natural oxide film. Thereafter, the substrate was loaded into the ALD chamber, and the substrate was heated to 350 ° C., and H ₂ O vapor was supplied into the chamber for 120 seconds to further etch the Ge oxide film. Subsequently, Hf [NCH ₃ C ₂ H ₅ ] ₄ as a metal oxide precursor, a first purge step, and H ₂ O vapor as an oxidizing agent were supplied at 350 ° C. on a substrate on which the Ge oxide film was etched by H ₂ O steam treatment. The cycle consisting of a step and a second purge step was repeated 40 times to form an HfO ₂ film, and then the substrate was unloaded from the ALD chamber. Thereafter, Pt was deposited on the HfO ₂ film to prepare a MOS capacitor.

<MOS capacitor comparative example 1>

A MOS capacitor was manufactured in the same manner as in Preparation Example 1, except that the step of loading the substrate into the ALD chamber and supplying H ₂ O vapor to further etch the Ge oxide film was omitted.

6 is a graph showing capacitance according to electrode voltages of MOS capacitors according to Preparation Example 1 and Comparative Example 1. FIG.

Referring to FIG. 6, the MOS capacitor according to Preparation Example 1 is more cumulative than the MOS capacitor according to Comparative Example 1. It can be seen that the capacitance is large and the hysteresis is reduced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, This is possible.

110: Ge-based semiconductor layer 120: Ge oxide film
130: dielectric film 140: conductive film
G: gate electrode S: source region
D: drain region

Claims (9)

Providing a substrate having a Ge-based semiconductor layer and a Ge oxide layer formed on the Ge-based semiconductor layer;
Loading the substrate into a deposition apparatus;
Etching the Ge oxide layer by supplying H ₂ O vapor on the substrate;
Depositing a dielectric film on the substrate on which the Ge oxide layer is etched without vacuum destruction; And
And unloading the substrate on which the dielectric film is deposited from a deposition apparatus. The method of claim 1,
And forming an inert gas on the substrate together with the H ₂ O vapor. The method of claim 1,
Supplying H ₂ O vapor on the substrate and depositing the dielectric film are performed in-situ in the same chamber of the deposition apparatus. The method of claim 1,
Supplying H ₂ O vapor on the substrate and depositing the dielectric film are performed without vacuum breaking in different chambers of the deposition apparatus. The method of claim 1,
The dielectric film is an oxide film. The method of claim 1,
Before loading the substrate into the deposition apparatus,
And repeatedly performing the HF aqueous solution cleaning and the deionized water cleaning on the substrate. delete The method of claim 1,
And supplying H ₂ O vapor onto the substrate, and heating the substrate to the dielectric film deposition temperature. Providing a substrate having a Ge-based semiconductor layer and a Ge oxide layer formed on the Ge-based semiconductor layer;
Loading the substrate into a deposition apparatus;
Etching the Ge oxide layer by supplying H ₂ O vapor on the substrate;
Depositing a dielectric film on the substrate on which the Ge oxide layer is etched without vacuum destruction;
Unloading the substrate on which the dielectric film is deposited from a deposition apparatus; And
Forming a conductive film on the dielectric film.

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