JPH0239523A - Method of forming film on semiconductor substrate - Google Patents

Abstract

PURPOSE:To enable a good quality of film to be formed while preventing damage to a substrate to be treated by doing cleaning treatment and film formation treatment in the same atmosphere, and also doing low energy sputter etching for the cleaning treatment. CONSTITUTION:With a vacuum load-lock room 7 as the center, at angle intervals of about 90 deg., plural, for example, three chambers 2 to 4 are arranged in the form of the same circumference through gate valves 5. And the cleaning treatment chamber 2 is composed of a high frequency electrode 7 being stored inside of it, a lower electrode 8, a high frequency power source 9 to apply high frequency to the high frequency electrode 7, and a DC power source 10 to apply DC substrate voltage to the lower electrode 8. And while maintaining the specified vacuum degree, treatment gas, for example, Ar gas is introduced from a gas introduction port 11. At this time, the specified high frequency voltage is applied to the high frequency electrode 7, and the specified substrate voltage is applied to the lower electrode 10. Ar gas introduced this way is converted into plasma by high frequency, and Ar ions in this plasma region (m) are applied to the surface of a substrate to be treated for etching. Accordingly; without giving damage to substrate to be treated, needless film such as SiO2 film, etc., can be removed, and a high quality of film can be formed.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to a method for forming a film on a semiconductor.

(Prior art) Conventionally, in film forming processes such as S1 epitaxial film formation and nitride film in semiconductor manufacturing processes, organic substances, etc. formed on the surface of the substrate to be processed, such as semiconductor wafer 1, are used as a pretreatment for the film forming process. A cleaning process is performed to remove the adsorbed impurity layer and natural oxide film layer.

A conventional cleaning treatment method is a wet etching method, and the wet etching method includes the following methods.

■H2so, :H202-4: Soak in solution 1 for 5 minutes.
2; ■Cleanse with ultrapure water for 10 minutes■Immerse in HF: H2O-1+100 solution for 1 minute■
Washing with ultrapure water for 10 minutes - Drying process The substrate to be processed thus treated was transported to a film forming apparatus and subjected to film forming processing.

However, in the above-mentioned cleaning process, the cleaned substrate is exposed to the atmosphere when it is transported to the film forming apparatus. It has been reported that an adsorbed molecular layer of impurities such as CH2)n is formed again, and if a film formation process is performed with such a thin film formed, the formed thin film and the substrate to be processed may come into close contact with each other. There was a problem in that it had poor properties and could not be used as an interface in the production of LSI devices. Further, even if the transportation work to the film forming apparatus is performed in a clean room, it is not possible to completely prevent dust from adhering to the substrate to be processed, which causes a decrease in yield.

Therefore, in order to solve these problems, a processing chamber for performing cleaning processing is provided in the film forming apparatus, and the cleaning processing and film forming process are performed without exposing the cleaned processed substrate to the atmosphere within the same apparatus housing. Processing devices have been developed to perform the processing.

As such a film forming apparatus, a single-wafer type so-called multi-chamber type CVD processing apparatus has been developed, which is equipped with a plurality of processing chambers (chambers) in the same atmosphere, for example, a vacuum container. After the substrate to be processed is cleaned in the processing chamber, the substrate to be processed is transported to the film-forming chamber for processing.

(Problem to be Solved by the Invention) However, in the conventional multi-chamber type film forming processing apparatus described above, cleaning processing of the processing target substrate is performed using high-energy plasma etching processing or an oxygen atmosphere inside the chamber to clean the processing target substrate. Processing is carried out by raising the temperature to a high temperature, for example 800°C, and irradiating it with ultraviolet rays.In both cases, the problem is that the substrate to be processed is damaged by heat and flying ions, and the yield is reduced. there were.

The present invention was made in order to solve the above-mentioned problems, and in addition to performing a cleaning process and a film forming process in the same atmosphere, the cleaning process is performed by low-energy sputter etching, so that the substrate to be processed can be etched. It is an object of the present invention to provide a method for forming a film on a semiconductor substrate, which can form a high-quality film while preventing damage to the semiconductor substrate.

[Structure of the Invention] (Means for Solving the Problems) The method of forming a film on a semiconductor substrate of the present invention includes a step of cleaning an unnecessary thin film on the surface of the substrate to be processed, and a step of cleaning the unnecessary thin film on the surface of the substrate to be processed after the cleaning process. In a method for forming a film on a semiconductor substrate, the method includes a film forming step of forming a predetermined thin film on a semiconductor substrate.
The cleaning step and the film forming step are performed in the same atmosphere, and the cleaning step is performed by sputter etching using ions having approximately the same energy as the bonding energy between the unnecessary thin film and the substrate to be processed. That is.

(Function) The present invention performs a cleaning process and a film forming process in the same device housing, and also performs a cleaning process by low energy sputter etching, thereby preventing damage to the substrate to be processed. It becomes possible to form a film of high quality.

(Example) Hereinafter, an example in which the present invention is applied to a multi-chamber type CVD apparatus for St epitaxial growth will be described with reference to the drawings.

A plurality of chambers 2.3.4, for example, three chambers, are arranged around the vacuum load-lock chamber 1 at angular intervals of about 90 degrees, each via a gate valve 5, in the same circumferential shape.

These chambers 2.3.4 are composed of a cleaning processing chamber 2 that removes unnecessary thin films such as natural oxide films formed on the substrate to be processed by low energy sputter etching, and a cleaning processing chamber 2 for removing unnecessary thin films such as natural oxide films formed on the substrate to be processed, and the substrate to be processed that has been cleaned. It is composed of a film formation processing chamber 3 for performing film formation processing, for example, Si epitaxial film formation, and a heat treatment chamber 4 for further processing the substrate to be processed on which the thin film is formed, for example, heat treatment in an atmosphere of N2 gas, etc. ing.

The substrate 6 to be processed, such as a semiconductor substrate, is transported into the vacuum load lock chamber 1 by a transport mechanism (not shown), where it is transferred through a procedure according to the processing content, for example, from chamber 1 → chamber 2 →
It is transported in the order of chamber 3 → chamber 4 and subjected to predetermined processing.

By the way, the cleaning processing chamber 2 is a chamber for performing low energy sputter etching on the substrate 6 to be processed, and its configuration is as shown in FIG.
a high-frequency electrode 7 housed therein, and a lower electrode 8 disposed opposite to the high-frequency electrode 7 and serving as a mounting table for the substrate 6 to be processed.
, a high frequency power supply for applying a predetermined high frequency to the high frequency electrode 7 , and a DC power supply 10 for applying a DC substrate voltage to the lower electrode 8 .

Etching control is performed by controlling the density of processing gas ions using high frequency power and controlling the ion energy incident on the substrate 6 to be processed using the substrate voltage.

Further, a gas inlet 11 for introducing an etching gas such as Ar gas is provided in the chamber wall near the high-frequency electrode 7, and a gas exhaust port 12 is provided in the chamber wall near the lower electrode 8. Ar gas introduced into the chamber 2 from the gas inlet 11 is exhausted from the gas exhaust port 12 to a vacuum mechanism (not shown).

A low energy sputter etching method using this chamber 2 will be explained below.

First, a processing gas such as Ar gas is introduced from the gas inlet 11 while maintaining a predetermined degree of vacuum, e.g. 10" Torr. At this time, a predetermined cylindrical frequency e.g.
A high frequency power of OOMHz is applied, while a predetermined substrate voltage, for example, a voltage within the range of -15 to +15V is applied to the lower electrode 10.

In this way, the introduced Ar gas is turned into plasma by high frequency waves, and etching is performed by irradiating the surface of the substrate to be processed with A' ions in this plasma region m.

In addition, in the method of this embodiment, the substrate voltage is -15 to +15V.
Since the voltage is set to be low, the energy of the A' ions incident on the substrate 6 to be processed is low, for example, several tens of eV.

Generally, the interatomic bonding energy between the semiconductor substrate and the 5102 film or adsorbed impurity molecular layer is about several tens of eV, so
By performing sputter etching with low energy ions having energy close to this bond energy, unnecessary thin films such as the 5i02 film can be removed without damaging the substrate to be processed.

After performing the cleaning process in chamber 2 in this way,
The substrate 6 to be processed is carried out into the vacuum load-lock chamber 1, and then carried into the chamber 3, where a film formation process, for example, St epitaxial film formation is performed. Then, after carrying out the substrate 6 to be processed into the load lock chamber again, if necessary, the substrate 6 to be processed is carried into the chamber 4 and predetermined processing is performed there.

In this way, after the substrate 6 to be processed is cleaned by low-energy sputter etching, the substrate 6 to be processed is subjected to a film forming process without being exposed to the atmosphere.
Film formation can be performed by completely removing the natural oxide film and adsorbed impurity layer formed on the substrate 6 to be processed, and high-quality film formation processing is possible. Furthermore, since the cleaning process is performed by low-energy sputter etching, damage to the substrate 6 to be processed during the cleaning process can be prevented, and the yield can be improved.

[Effects of the Invention] As explained above, according to the method for forming a film on a semiconductor substrate of the present invention, the natural oxide film and adsorbed impurity layer formed on the substrate to be processed can be removed without damaging the semiconductor substrate. Since the film formation process can be performed with complete removal, a high quality film can be formed and the yield can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a mulch chamber type CVD apparatus to which an embodiment of the method of the present invention is applied, and FIG. 2 is a diagram showing the configuration of the cleaning processing chamber of the embodiment of FIG. 1. 1...Vacuum load lock chamber, 2...Processing chamber for low energy sputter etching, 3.4
. . . Chamber for film formation 6 . . . Substrate to be processed, 7 . . . High frequency electrode, 8 . . . Lower electrode.

Claims (1)

[Claims] A method for forming a film on a semiconductor substrate, which comprises a step of cleaning an unnecessary thin film on the surface of a substrate to be processed, and a film forming step of forming a predetermined thin film on the cleaned substrate. The cleaning step and the film forming step are performed in the same atmosphere, and the cleaning step is performed by sputter etching using ions having an energy substantially equal to the bonding energy between the unnecessary thin film and the substrate to be processed. Characteristic method for forming films on semiconductor substrates.