JP2956347B2 - Semiconductor substrate cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a semiconductor substrate, and more particularly to a cleaning method using vapor phase cleaning using steam.

[0002]

2. Description of the Related Art Conventionally, as a method for cleaning contaminated metals on a semiconductor substrate, an immersion wet cleaning method in which a semiconductor substrate is immersed in a chemical bath containing a cleaning liquid such as hydrochloric acid-hydrogen peroxide or sulfuric acid-hydrogen peroxide has been widely used. Have been.

Recently, in order to solve these problems of the immersion wet cleaning method, a method of treating a semiconductor substrate with a hydrogen fluoride vapor and then rinsing with pure water as shown in the configuration diagram of FIG. Proposed. The semiconductor substrate 1 is a rotary support 2
And is placed in a synthetic resin chamber 7 such as Teflon which does not react with hydrogen fluoride. First, the inside of the synthetic resin chamber 7 is filled with nitrogen from a nitrogen inlet 11 through an optional mass flow controller 9 and a valve 8. Subsequently, while rotating the turntable 2, the steam generated by the steam generator 4 is introduced into the synthetic resin chamber 7 together with nitrogen to uniformly wet the surface of the semiconductor substrate 1. This is important for cleaning to proceed uniformly over the entire surface of the semiconductor substrate 1.

After exhausting the gas through the exhaust port 12 while flowing nitrogen into the synthetic resin chamber 7 again, the heater 6
Hydrogen fluoride vapor is generated by the hydrogen fluoride container 5 heated to 0 to 80 ° C. The hydrogen fluoride vapor is supplied to the synthetic resin chamber 7 together with nitrogen by the mass flow controller 9.
The washing is carried out. During cleaning, the turntable 2 is rotated for uniform cleaning. Cleaning proceeds by removal of oxides by hydrogen fluoride vapor. The cleaning is completed by filling the inside of the synthetic resin chamber 7 with nitrogen.

[0005]

FIG. 7 is a graph showing the problems of the conventional immersion wet cleaning method, and shows the number of iron atoms per square centimeter of the surface of the semiconductor substrate as the number of processed semiconductor substrates increases. Here, A in the figure is an ammonia water-hydrogen peroxide-based cleaning liquid, and B is a hydrochloric acid-hydrogen peroxide-based cleaning liquid. Iron adhered to the surface of a semiconductor substrate is known as a metal that significantly deteriorates the dielectric strength of an oxide film and deteriorates the reliability of an integrated circuit.

In the conventional immersion wet cleaning method, a semiconductor substrate is continuously treated in a cleaning liquid,
Contaminants on the surface of the semiconductor substrate accumulate in the liquid and redeposit on other semiconductor substrates. The amount of adhesion increases with the number of processed sheets, and there is a problem that the cleaning effect is reduced. Further, in the conventional immersion wet cleaning method, a plurality of cleaning tanks are combined, so that there is also a problem that the apparatus tends to be large.

In order to solve the above problems, a method of treating a semiconductor substrate with hydrogen fluoride vapor and then rinsing with pure water has been proposed. However, a method of removing contaminants having a low ionization tendency, such as copper and gold, has been proposed. There is a problem that there is no ability to remove, and there is no ability to remove contaminants implanted in the semiconductor substrate by ion implantation or the like.

[0008]

According to the present invention, there is provided a semiconductor substrate cleaning method for cleaning a semiconductor substrate in a vapor phase in a hydrogen fluoride vapor containing ozone followed by rinsing with pure water. Content is 0.1 to 20 vol%
And the temperature of the semiconductor substrate to be subjected to the gas phase cleaning process is 7
It is characterized by a temperature range of 0 to 120 ° C.

[0009]

By heating the semiconductor substrate, the ability of the semiconductor substrate to be oxidized by ozone is increased, and hydrogen fluoride is continuously removed from the oxide, and is implanted into the semiconductor substrate by ion implantation or the like. It is possible to remove even pollutants.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a semiconductor substrate cleaning apparatus according to a first embodiment of the present invention. The semiconductor substrate 1 is supported by a rotary support 2 and placed in a synthetic resin chamber 7 such as Teflon which does not react with hydrogen fluoride or ozone. First, the interior of the synthetic resin chamber 7 starts from the nitrogen inlet 11.
Nitrogen is charged through optional mass flow controller 9 and valve 8.

Subsequently, while rotating the turntable 2, the steam generated by the steam generator 3 is introduced into the synthetic resin chamber 7 together with the nitrogen to uniformly wet the surface of the semiconductor substrate 1. This is important for cleaning to proceed uniformly over the entire surface of the semiconductor substrate 1. After exhausting gas through the exhaust port 12 while flowing nitrogen into the synthetic resin chamber 7 again, hydrogen fluoride vapor is generated in the hydrogen fluoride container 5 heated to 30 to 80 ° C. by the heater 6.

The hydrogen fluoride vapor is introduced into the synthetic resin chamber 7 together with nitrogen by the mass flow controller 9. At the same time, the oxygen introduced from the oxygen inlet 10 is ozonized by the ozone generator 3, adjusted to 0.1 to 20 vol% by the mass flow controller 9, and introduced into the synthetic resin chamber 7. , Washing is performed. The amount of ozone introduced is preferably set in this range because the cleaning effect is not obtained at 0.1 vol% or less and the substrate surface is roughened at 20 vol% or more. During cleaning, the turntable 2 is rotated for uniform cleaning. The cleaning proceeds by oxidation of the surface of the semiconductor substrate 1 with ozone and removal of the oxide by hydrogen fluoride vapor.

The cleaning is completed by filling the interior of the synthetic resin chamber 7 with nitrogen. Before that, by flowing only one of hydrogen fluoride vapor and ozone into the synthetic resin chamber 7, the presence or absence of an oxide film on the surface of the semiconductor substrate 1 after cleaning can be selected. The state is feasible. After cleaning, the synthetic resin chamber 7
Is rinsed with pure water and then dried.

The effects of the present invention are shown in the graphs of FIGS.

FIG. 3 shows a comparison of the effect of removing contaminants by cleaning a semiconductor substrate intentionally contaminated with metal by the conventional cleaning methods A, B, and C and the cleaning method of the present invention. here,
In the figure, A is ammonia water-hydrogen peroxide, B is hydrochloric acid-hydrogen peroxide immersion wet cleaning method, and C is pure water rinse after treatment with hydrogen fluoride vapor. It can be seen that the present invention shows a contaminant removal effect equal to or higher than that of the conventional cleaning method for any metal of aluminum, iron and copper.

FIG. 4 is a graph showing the concentration of iron contamination on the surface of a substrate with the number of processed semiconductor substrates. In the conventional immersion wet cleaning methods A and B, the contamination concentration increases with the number of processed sheets, but the tendency is not seen in C or the present invention.

FIG. 2 is a configuration diagram of a semiconductor cleaning apparatus according to a second embodiment of the present invention. This embodiment is characterized in that the semiconductor substrate 1 is heated to 70 to 120 ° C. using the heater 13 in addition to the first embodiment. In the cleaning method of the first embodiment, by continuously heating the semiconductor substrate 1 to 70 to 120 ° C., the oxidizing action of ozone is increased, and the oxidation of the surface of the semiconductor substrate 1 and contaminants is further promoted. The oxide is
It is continuously removed with hydrogen fluoride vapor. Therefore, even contaminants implanted inside the substrate by ion implantation etc.
It can be removed.

FIG. 5 is a graph showing the relationship between the substrate temperature and the effect of removing contamination. The semiconductor substrate used here is one in which metal contaminants are implanted into the substrate by ion implantation. It can be seen that as the temperature increases, the effect of removing contaminants appears more remarkably. It can be seen that the removal effect is almost 100% at 70 ° C. or higher and is saturated. However, when the substrate temperature exceeds 120 ° C., the erosion of the semiconductor substrate progresses, and the surface of the substrate becomes rough. Therefore, the temperature of the semiconductor substrate is preferably 70 to 120C, and more preferably 90C.

Further, in the above embodiment, it is not necessary to combine several types of cleaning tanks, so that space saving of the cleaning apparatus can be achieved.

[0021]

As described above, the present invention can be used in the range of 0.1 to 0.1.
Since the semiconductor substrate is treated in a hydrogen fluoride vapor containing 20 vol% ozone, there is no increase in the surface contamination concentration due to the number of treatments as in the immersion wet cleaning method, and the cleaning effect is also a conventional typical one. More than a simple cleaning method.

In addition, by performing the same treatment while heating the semiconductor substrate to 70 to 120 ° C., preferably 90 ° C., it is possible to remove even contaminants implanted into the semiconductor substrate by ion implantation or the like. Is possible. Further, according to the present invention, since it is not necessary to combine several types of cleaning tanks, space saving of the cleaning device is also achieved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a first embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a second embodiment of the present invention.

FIG. 3 is a graph showing the effect of the present invention.

FIG. 4 is a graph showing the effect of the present invention.

FIG. 5 is a graph showing the effect of the present invention.

FIG. 6 is a configuration diagram for explaining a conventional cleaning method.

FIG. 7 is a graph showing a problem of the related art.

[Explanation of symbols]

 Reference Signs List 1 semiconductor substrate 2 turntable 3 ozone generator 4 steam generator 5 hydrogen fluoride container 6 heater 7 synthetic resin chamber 8 valve 9 mass flow controller 10 oxygen inlet 11 nitrogen inlet 12 exhaust outlet 13 heater A ammonia water Cleaning method using hydrogen peroxide B Cleaning method using hydrochloric acid-hydrogen peroxide C Cleaning method in which pure water is rinsed after treatment with hydrogen fluoride vapor

Claims (1)

(57) [Claims] 1. A method for cleaning a semiconductor substrate in which a semiconductor substrate is subjected to a gas phase cleaning process in ozone-containing hydrogen fluoride vapor and then rinsed with pure water, wherein the ozone content is 0.1 to 20 vol.
1%, and the temperature of the semiconductor substrate to be subjected to the gas phase cleaning treatment is in a temperature range of 70 to 120 ° C.