CN105336596B - A kind of preparation method of high-k boundary layer - Google Patents

Abstract

A method for preparing a high dielectric constant interface layer, comprising: step S1: providing a silicon _- based substrate, and cleaning the silicon _- based substrate with a mixed solution of _H2SO4 and H2O2 _; step S2: using RCA Cleaning method to clean the silicon-based substrate; step S3: use HF solution to clean the silicon-based substrate; step S4: use thermal oxidation method to grow SiO ₂ /SiON transition layer; step S5: use SC1 chemical solution cleaning process to clean SiO ₂ /SiON transition layer; step S6: depositing a high dielectric constant gate dielectric layer on the SiO ₂ /SiON transition layer cleaned by SC1 chemical solution. The high dielectric constant interface layer obtained by the preparation method of the present invention can effectively reduce the interface state density of the high dielectric constant interface layer, and improve the properties of the subsequently grown hafnium-based gate dielectric layer, thereby improving device performance.

Description

A kind of preparation method of high dielectric constant interface layer

technical field

The invention relates to the technical field of semiconductor manufacturing, in particular to a preparation method of a high dielectric constant interface layer.

Background technique

With the continuous development of large-scale integrated circuit technology, the feature size of the metal oxide semiconductor field effect transistor (MOSFET), which is the core device of silicon-based integrated circuits, has been continuously shrinking in accordance with Moore's law, so the gate dielectric layer must be reduced. thickness to maintain good performance by reducing the length of the gate. However, the thickness of the gate dielectric layer of the existing field effect transistor (MOS) is getting smaller and smaller, which is already approaching its limit value. Therefore, in order to reduce gate leakage, using a gate dielectric layer with a high dielectric constant (k) allows a smaller physical thickness while maintaining the same effective thickness.

In order to reduce the interface state density between the high dielectric constant gate dielectric layer and the silicon-based substrate, generally by adding a gate dielectric transition layer with almost no defects between the two, such as SiO ₂ /SiON, commonly known as high dielectric constant Electricity constant interface layer. However, since the high-permittivity interface layer grown only by traditional thermal oxidation method is not easy to form a Hf-Si-O mixed structure with the high-permittivity hafnium-based gate dielectric material, the interface state density between the two If it is too high, it will affect the performance of the device.

It has become one of the technical problems to be solved urgently by those skilled in the art to seek a preparation method of a high-permittivity interface layer that can effectively reduce the interface state density between the high-permittivity hafnium-based dielectric material and the silicon-based substrate.

Therefore, aiming at the problems existing in the prior art, the designer of this case relied on years of experience in this industry to actively research and improve, so there is a preparation method of a high dielectric constant interface layer of the present invention.

Contents of the invention

The present invention aims at the fact that in the prior art, it is difficult to form a Hf-Si-O mixed structure between the high-permittivity interface layer grown only by the traditional thermal oxidation method and the high-permittivity hafnium-based gate dielectric material, so that the two A high dielectric constant interface layer is provided for defects such as the interface state density is too high, thereby affecting the performance of the device.

In order to realize the purpose of the present invention, the present invention provides a kind of preparation method of high dielectric constant interface layer, the preparation method of described high dielectric constant interface layer, comprises:

Executing step S1: providing a silicon-based substrate, and cleaning the silicon-based substrate with a mixed solution of H ₂ SO ₄ and H ₂ O ₂ ;

Executing step S2: cleaning the silicon-based substrate by RCA cleaning method;

Executing step S3: cleaning the silicon-based substrate with HF solution;

Executing step S4: growing a SiO ₂ /SiON transition layer by a thermal oxidation method;

Executing step S5: using SC1 (NH ₄ OH/H ₂ O ₂ /H ₂ O) chemical solution cleaning process to clean the SiO2/SiON transition layer;

Executing step S6: depositing a high dielectric constant gate dielectric layer on the SiO ₂ /SiON transition layer cleaned by the SC1 chemical solution.

Optionally, the thickness of the SiO ₂ /SiON transition layer obtained after performing step S4 is 0-10 angstroms.

Optionally, the SiO ₂ /SiON transition layer has a hydroxyl group (—OH) after step S5 is performed.

Optionally, the SiO ₂ /SiON transition layer having a hydroxyl group (-OH) has a thickness of 0-8 angstroms.

Optionally, the thermal oxidation method to grow the SiO ₂ /SiON transition layer further includes thermal nitridation and plasma nitridation auxiliary doping process.

Optionally, the SiO ₂ /SiON transition layer is cleaned using an SC1 (NH ₄ OH/H ₂ O ₂ /H ₂ O) chemical solution cleaning process, which further includes a cleaning method with a doping property.

Optionally, the cleaning method of the doping property is a Siconi cycle cleaning method and a chemical oxidation method to dope the interface layer with fluorine (F) element.

Optionally, the high dielectric constant gate dielectric layer is a hafnium-based gate dielectric layer.

In summary, the high-permittivity interface layer obtained by the method for preparing the high-permittivity interface layer of the present invention can effectively reduce the interface state density of the high-permittivity interface layer, and increase the density of the subsequently grown hafnium-based gate dielectric. The properties of the layer, thereby improving the performance of the device.

Description of drawings

Fig. 1 shows the flow chart of the preparation method of high dielectric constant interfacial layer of the present invention;

FIG. 2 is a comparison diagram of the interface state density of the high dielectric constant interface layer obtained by the preparation method of the high dielectric constant interface layer of the present invention and the traditional high dielectric constant interface layer.

Detailed ways

In order to illustrate the technical content, structural features, achieved goals and effects of the present invention in detail, the following will be described in detail in conjunction with the embodiments and accompanying drawings.

In the present invention, in order to reduce the interface state density between the high dielectric constant gate dielectric layer and the silicon-based substrate, preferably, a High dielectric constant interfacial layer. Without limitation, the high dielectric constant gate dielectric layer is a hafnium-based gate dielectric layer. The high dielectric constant interface layer is a SiO ₂ /SiON transition layer, and the SiO ₂ /SiON transition layer has a hydroxyl group (—OH).

Please refer to FIG. 1 . FIG. 1 is a flowchart of a method for preparing a high dielectric constant interface layer of the present invention. The preparation method of the high dielectric constant interface layer includes:

Executing step S1: providing a silicon-based substrate, and cleaning the silicon-based substrate with a mixed solution of H ₂ SO ₄ and H ₂ O ₂ ;

Executing step S2: cleaning the silicon-based substrate by RCA cleaning method;

Executing step S3: cleaning the silicon-based substrate with HF solution;

Executing step S4: growing a SiO ₂ /SiON transition layer by a thermal oxidation method;

Executing step S5: cleaning the SiO ₂ /SiON transition layer by SC1 (NH ₄ OH/H ₂ O ₂ /H ₂ O) chemical solution cleaning process;

Executing step S6: depositing a high dielectric constant gate dielectric layer on the SiO ₂ /SiON transition layer cleaned by the SC1 chemical solution.

In order to more intuitively disclose the technical solutions of the present invention and highlight the beneficial effects of the present invention, the methods and principles of the present invention will now be described in conjunction with specific embodiments. In the specific implementation manner, the thickness and process method of the high dielectric constant interface layer are just examples, and should not be regarded as limitations on the technical solution of the present invention. The preparation method of the high dielectric constant interface layer includes:

Executing step S1: providing a silicon-based substrate, and cleaning the silicon-based substrate with a mixed solution of H ₂ SO ₄ and H ₂ O ₂ to remove organic matter on the surface of the silicon-based substrate;

Executing step S2: cleaning the silicon-based substrate by using an RCA cleaning method; wherein, the RCA cleaning method can be a traditional wet chemical cleaning method, which will not be repeated here.

Executing step S3: cleaning the silicon-based substrate with HF solution to effectively remove the native oxide layer on the surface of the silicon-based substrate, thereby reducing the thickness of the interface layer;

Executing step S4: growing a SiO ₂ /SiON transition layer by a thermal oxidation method;

Executing step S5: using SC1 (NH ₄ OH/H ₂ O ₂ /H ₂ O) chemical solution cleaning process to clean the SiO ₂ /SiON transition layer, so that the SiO ₂ /SiON transition layer has hydroxyl (-OH) ;

Executing step S6: depositing a high dielectric constant gate dielectric layer on the SiO ₂ /SiON transition layer cleaned by the SC1 chemical solution. For example, the high dielectric constant dielectric layer is a hafnium-based gate dielectric layer.

More specifically, for example, in the step S4, the thermal oxidation method grows the SiO ₂ /SiON transition layer, further including thermal nitridation and plasma nitridation auxiliary doping process. The thickness of the SiO ₂ /SiON transition layer is 0-10 angstroms. In the step S5, the SiO ₂ /SiON transition layer is cleaned using an SC1 (NH ₄ OH/H ₂ O ₂ /H ₂ O) chemical solution cleaning process, so that the SiO ₂ /SiON transition layer has hydroxyl ( -OH), the thickness of the SiO ₂ /SiON transition layer with hydroxyl group (-OH) is 0-8 angstroms. In step S5, the SiO ₂ /SiON transition layer is cleaned by SC1 (NH ₄ OH/H ₂ O ₂ /H ₂ O) chemical solution cleaning process, further including a cleaning method with doping properties and other chemical cleaning processes, For example, the existing Siconi cycle cleaning method and chemical oxidation method make the interface layer doped with fluorine (F) elements to improve the NBTI effect of the device.

Please refer to Fig. 2, and refer to Fig. 1 in conjunction with, Fig. 2 shows the interface state density difference between the interface state density of the high dielectric constant interface layer obtained by the preparation method of the high dielectric constant interface layer of the present invention and the traditional high dielectric constant interface layer Compare chart. As a person skilled in the art, it is easy to understand that after step S4, that is, the SiO ₂ /SiON transition layer is grown by thermal oxidation, step S5 is performed, and SC1 (NH ₄ OH/H ₂ O ₂ /H ₂ O) chemical The solution cleaning process cleans the SiO ₂ /SiON transition layer, so that the SiO ₂ /SiON transition layer has a hydroxyl group (-OH), and the hydroxyl group (-OH) of the SiO ₂ /SiON transition layer is easy to be used as a high dielectric The constant hafnium-based gate dielectric layer forms a mixed structure of Hf-Si-O, thereby improving the interface state between the two, significantly reducing the interface state density, and improving the properties of the subsequently grown hafnium-based gate dielectric layer film, improving the device performance.

Obviously, the high dielectric constant interface layer obtained by the preparation method of the high dielectric constant interface layer of the present invention can effectively reduce the interface state density of the high dielectric constant interface layer, and improve the density of the subsequently grown hafnium-based gate dielectric layer. properties, thereby improving the performance of the device.

In summary, the high-permittivity interface layer obtained by the method for preparing the high-permittivity interface layer of the present invention can effectively reduce the interface state density of the high-permittivity interface layer, and increase the density of the subsequently grown hafnium-based gate dielectric. The properties of the layer, thereby improving the performance of the device.

Those skilled in the art will appreciate that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, if any modification or variation falls within the scope of protection of the appended claims and their equivalents, the present invention is deemed to cover such modification and variation.

Claims (8)

1. a kind of preparation method of high-k boundary layer, the high-k boundary layer are located at hafnium base gate dielectric layer and silicon Between base substrate, which is characterized in that the preparation method of the high-k boundary layer, including：

Perform step S1：Silicon-based substrate is provided, and utilizes H₂SO₄And H₂O₂Mixed solution the silicon-based substrate is cleaned；

Perform step S2：The silicon-based substrate is cleaned using RCA ablutions；

Perform step S3：The silicon-based substrate is cleaned using HF solution；

Perform step S4：SiO is grown using thermal oxidation method₂/ SiON transition zones；

Perform step S5：Using SC1 (NH₄OH/H₂O₂/H₂O) chemical solution cleans technique cleans the SiO₂/ SiON transition zones, So that the SiO₂/ SiON transition zones have hydroxyl (- OH), further using Siconi wash cycles method and chemical oxidation side Formula makes boundary layer adulterate fluorine (F) element, to improve the NBTI effects of device, the SiO₂The hydroxyl (- OH) of/SiON transition zones with The hafnium base gate dielectric layer forms the mixed structure of Hf-Si-O；

Perform step S6：In the SiO Jing Guo SC1 chemical solution cleans₂Depositing high dielectric constant gate dielectric layer on/SiON transition zones.

2. the preparation method of high-k boundary layer as described in claim 1, which is characterized in that the institute after step S4 is performed The SiO of acquisition₂The thickness of/SiON transition zones is 0~10 angstrom.

3. the preparation method of high-k boundary layer as described in claim 1, which is characterized in that the institute after step S5 is performed State SiO₂/ SiON transition zones have hydroxyl (- OH).

4. the preparation method of high-k boundary layer as claimed in claim 3, which is characterized in that it is described have hydroxyl (- OH SiO)₂The thickness of/SiON transition zones is 0~8 angstrom.

5. the preparation method of high-k boundary layer as described in claim 1, which is characterized in that the thermal oxidation method growth SiO₂/ SiON transition zones further comprise the attached doping process of tropical resources, pecvd nitride.

6. the preparation method of high-k boundary layer as described in claim 1, which is characterized in that using SC1 (NH₄OH/ H₂O₂/H₂O) chemical solution cleans technique cleans the SiO₂/ SiON transition zones further comprise the cleaning with doping property Method.

7. the preparation method of high-k boundary layer as claimed in claim 6, which is characterized in that described to adulterate the clear of property Washing method makes boundary layer adulterate fluorine (F) element for Siconi wash cycles method and chemical oxidation mode.

8. the preparation method of the high-k boundary layer as described in claim 1~7 any claim, which is characterized in that The high-dielectric-coefficient grid medium layer is hafnium base gate dielectric layer.