JP2002134454A - Contamination removal method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove micro-quantity of contamination, especially metallic contamination and organic contamination on a wafer, which obstructs the yield improvement of higher density integrated circuits formed on a substrate, such as a semiconductor wafer. SOLUTION: A means which etches a substrate and a film and a means, which changes contaminants into substances with high vapor pressures, are used simultaneously, alternately, or periodically to remove the metallic contaminants and organic contaminants on the wafer. With such a constitution, the yield of electronic components, such as semiconductor devices, can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing contaminants for cleaning the surface of a semiconductor substrate such as a semiconductor wafer in a semiconductor device manufacturing process or the like.

[0002]

2. Description of the Related Art In recent years, the degree of integration of integrated circuits formed on the surface of a substrate such as a semiconductor wafer has been increasing more and more, and the line width of a pattern has been reduced. Minimum processing size is 6
0.3μm with 4Mbit DRAM, 256MbitDR
AM is 0.2 μm, and a very small amount of contamination in the manufacturing process significantly reduces product quality and yield.
Of particular concern as trace contamination are Fe, Cu, N
Metal contamination such as i and organic contamination.

As a means for cleaning the substrate surface against the above-mentioned contamination, RCCA Review 31 (1970), No. 1
Pages 87 to 206 [RCA Review, 31
(1970) P.A. 187-206], a method of heating a mixture of aqueous ammonia and hydrogen peroxide or a mixture of hydrochloric acid and aqueous hydrogen peroxide to about 80 ° C. and immersing the wafer in the mixture (RCA cleaning) is known. Generally done. Since these wet cleaning methods are performed in liquid,
It is expected that a limit will occur sooner or later due to the fact that re-adhesion of contamination is inevitable, or the liquid permeation into a high step portion or a complicated element structure is not sufficient. Therefore, a cleaning method has been proposed that removes contamination on a wafer by active molecules or active atoms excited by plasma, light, or heat, in which re-adhesion of contamination cannot occur in principle and high-step portions can be easily cleaned. I have. This is called dry cleaning.
As described in Japanese Patent Application Laid-Open No. 0-75324, a method for removing metal contamination on a Si wafer by irradiating ultraviolet light to chlorine gas, and as described in Japanese Patent Application Laid-Open No. 4-75324, For removing organic substances on a Si wafer by applying plasma to the substrate.

[0004]

As described above, the dry cleaning method is not expected to achieve re-adhesion in principle, so that high cleanliness is expected to be realized. The cleanliness did not reach a sufficiently good value, indicating that the removal of contamination was insufficient. This is because some of the contaminants adhering to the wafer surface are removed, but others can enter the substrate or film by using a known technique and cannot be removed by a known technique. It is thought to be. Heating the wafer to about 150 to 200 [deg.] C. is considered to be a cause. However, without heating, the removal effect is reduced, which can be said to be a major problem of the above-described conventional technology.

[0005] Even in the case of contamination in a substrate or a film, in an actual production line, device characteristics are degraded as a heat treatment step or the like is performed, and it is expected that a serious problem will occur.

Therefore, in order to manufacture a semiconductor device such as a semiconductor integrated circuit at a high yield, it is indispensable to develop a dry cleaning method capable of simultaneously removing contamination that has entered a substrate or a film. .

An object of the present invention is to solve the above-mentioned conventional problems, and a first object of the present invention is to provide a method for removing metal or organic contaminants that have entered a substrate or a film. An object of the present invention is to provide a cleaning apparatus using the same, and a cleaning and film forming apparatus combining a cleaning apparatus and a film forming apparatus.

[0008]

SUMMARY OF THE INVENTION The basic concept of the present invention is to remove contaminants in a substrate or a film by removing the contamination while etching the substrate or the film. Experiments have confirmed a great effect that the contamination removal ability is significantly improved by combining the conventional contamination removal method with etching. Specifically, Si
For a substrate, substrate etching is realized by combining a means for oxidizing the surface and a means for etching a generated oxide film. For a film, particularly an oxide film, the film is etched by means for etching the oxide film. The object of the present invention can be achieved by simultaneously or alternately combining means for reacting with metal contamination to change to a substance having a high vapor pressure or means for reacting with organic contamination to change to a substance having a high vapor pressure. As will be described later, the amount of etching of the substrate or the film is a point for realizing the present invention.

In the cleaning apparatus of the present invention, a gas supply system for realizing the above method, a plasma generating section for exciting the gas, an ultraviolet light source or a heating section are combined with a vacuum apparatus capable of transporting a wafer or the like. It is a thing. Further, by combining this cleaning apparatus with a film forming apparatus or the like, an integrated cleaning and film forming processing apparatus is configured.

It is considered that the contamination that has entered the substrate or the film can be removed by simply etching the substrate or the film. As a result of many experiments, the inventor has found that the point of etching the substrate or the film is the key to enhancing the effect of removing contamination. FIG. 2 shows a wafer treated with the method shown in Example 1 on a wafer contaminated with Fe (without a thermal oxide film) by a method described later in the example, and a wafer contaminated with Cu (without a thermal oxide film). FIG. 4 shows the relationship between the amount of wafer etching and the amount of surface contamination for the substrate treated by the method shown in Example 1. FIG.

In each case, a satisfactory effect of removing contamination was observed at an etching amount of 50 ° or more. In addition, the temperature fell below the detection limit of the evaluation device at about 300 °. Therefore, the etching amount needs to be 50 ° or more, and processing up to about 300 ° is preferable.

[0012] In the means for reacting with contamination to change into a substance having a high vapor pressure, the vapor pressure of the substance is desirably about 10 to ⁵ Pa or more at room temperature.
This is obtained from the following calculation. First, the total amount of contamination to be removed is determined. The metal contamination generated in the production line is about 10 ¹³ / cm ^{2 in} most cases, and is about 7 × 10 ¹⁵ at a wafer diameter of 300 mm. This is about 10 to ⁸ moles. Now, assuming that the vapor pressure p of the reaction product, the volume V of the processing vessel, and the evacuation speed L of the vacuum apparatus are, the amount (mol) of the reaction product in the gas state in the processing vessel is pV / RT, and 1 in the vessel. Since the time required for exhausting once is V / T, the amount (mol) of the reaction product that can be exhausted per second is pL / RT. Here, T is an absolute temperature, and R is a gas constant. Therefore, in order to remove the above amount of contamination in 10 seconds or less, 10 to ⁹ RT / L <p
Must. Assuming that the unit of pressure is atm and the unit of volume is 1, R = 0.082, L = 200, T
= 300, p> 10 to ¹⁰ atm is obtained.
Here, it is necessary that 1 atm = 10 ⁵ pa.

In view of the principle of the present invention, it is clear that the present invention is also effective for contamination existing in the film before cleaning. However, the required amount of etching depends on the distribution of contamination in the film, and thus cannot be particularly limited.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

Embodiment 1 First, a method for preparing a contaminated wafer used in the study will be described. Experiments were performed on the following two types of wafers.

(1) A wafer immersed in hydrofluoric acid.

(2) A wafer on which a thermal oxide film is formed at 950 ° C. for 60 minutes in an oxygen atmosphere.

The contamination by metal ions is Ni, Fe, C
The wafer was immersed in an aqueous solution to which a predetermined amount of a standard reagent for atomic absorption of u was added for a certain period of time, washed with water, and dried. The amount of metal contamination on the wafer was measured in advance by total reflection X-ray fluorescence.

Using the wafer (1) on which a thermal oxide film is not formed and causing contamination, a cleaning gas 4 is introduced into the wafer 1 as shown in FIG.
Alternatively, it was excited by ultraviolet rays 6. The generated active molecules or atoms react with the substrate to etch or contaminate it. Specifically, the following treatment was performed, and the change in the amount of contamination was measured. The processing time is set to a value at which the etching amount is about 300 °, and differs depending on each experiment.

The mixed gas of O ₂ + NF ₃ + Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 300 ° C.

Plasma is applied to a mixed gas of O ₂ + CF ₄ + Cl ₂ . Wafer temperature about 300 ° C.

Plasma is applied to a mixed gas of O ₂ + SF ₆ + Cl ₂ and irradiated with ultraviolet light. Wafer temperature about 300
° C.

The Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 300 ° C.

A plasma is applied to a gas mixture of O ₂ + NF ₃ . Wafer temperature about 300 ° C.

Plasma is applied to a gas mixture of O ₂ + CF ₄ . Wafer temperature about 300 ° C.

Plasma is applied to a gas mixture of O ₂ + SF ₆ . Wafer temperature about 300 ° C.

A plasma is applied to O ₂ . Wafer temperature about 300 ° C.

In the above treatments, the wafer is heated in O ₂ to oxidize the wafer surface, the fluorine gas is excited by plasma or ultraviolet light to etch the oxide film, and Cl ₂ is plasma or It is excited by ultraviolet light, reacts with metal contamination, and is converted into a substance with a high vapor pressure and removed. What is shown here is merely an example, and the heating temperature, the combination of the used gases, and the like are not limited to those described above. Or, it is a comparative example according to the prior art. Examples 2, 3, 5,
The value in the comparative example is better than that of 7, which is considered to be because chlorine gas etches the silicon surface and also removes contamination in the substrate. However, the effect is clearly inferior to the present invention.

Is for organic matter contamination, and O ₂
Heating the wafer in the inside, oxidizing the wafer surface, exciting the fluorine-based gas using plasma and etching the oxide film,
O ₂ is excited by plasma to react with organic contaminants and is removed by converting it into a substance having a high vapor pressure. What is shown here is merely an example, and the heating temperature, the combination of the used gases, and the like are not limited to those described above. Is a comparative example according to the prior art.

Table 1 shows the change in the amount of contamination when the above treatment was applied to each contamination.

[0031]

[Table 1]

It can be seen that both metal contamination and organic matter contamination are significantly reduced as compared with the comparative example. (Embodiment 2) Using the wafer of (2) on which the thermal oxide film is formed as shown in Embodiment 1 and causing contamination,
As shown in FIG. 1B, a cleaning gas 4 was introduced, and was excited by plasma 5 or ultraviolet light 6. The generated active molecules or atoms react with the substrate to etch or contaminate it. Specifically, the following treatment was performed, and the change in the amount of contamination was measured. The processing time is set to a value at which the etching amount is about 300 °, and differs depending on each experiment.

The mixed gas of NF ₃ + Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 150 ° C.

Plasma is applied to a mixed gas of CF ₄ + Cl ₂ . Wafer temperature about 150 ° C.

Plasma is applied to a mixed gas of SF ₆ + Cl ₂ and irradiated with ultraviolet light. Wafer temperature about 150 ° C.

The Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 150 ° C.

A plasma is applied to a gas mixture of O ₂ + NF ₃ . Wafer temperature about 150 ° C.

Plasma is applied to a mixed gas of O ₂ + CF ₄ . Wafer temperature about 150 ° C.

Plasma is applied to the gas mixture of O ₂ + SF ₆ . Wafer temperature about 150 ° C.

The mixed gas of O ₃ + NF ₃ is irradiated with ultraviolet light. Wafer temperature about 150 ° C.

A plasma is applied to O ₂ . Wafer temperature about 150 ° C.

In the above treatments, the fluorine-based gas is excited by using plasma or ultraviolet light to etch the oxide film, and Cl ₂ is excited by plasma or ultraviolet light to react with metal contamination to cause a high vapor pressure. It is changed to a substance and removed. What is shown here is merely an example, and the heating temperature, the combination of the used gases, and the like are not limited to those described above. Or, it is a comparative example according to the prior art.

[0043] ~ is a fluorine-based gas to etch the oxide film is excited by a plasma or ultraviolet light, O ₂
Is excited by plasma or O ₃ is excited by ultraviolet light to react with organic contaminants and remove them by converting them into substances having a high vapor pressure. What is shown here is merely an example, and the heating temperature, the combination of the used gases, and the like are not limited to those described above. Is a comparative example according to the prior art.

Table 2 shows the change in the amount of contamination when the above treatment was applied to each contamination.

[0045]

[Table 2]

It can be seen that both metal contamination and organic matter contamination are significantly reduced as compared with the comparative example. (Embodiment 3) As shown in FIG. 1 (c), after an oxide film 2 is formed on a Si wafer 1 and a hole 3 is formed by a lithography technique, metal contamination and organic matter contamination are carried out by the method shown in the above Embodiment 1. Was generated. A cleaning gas 4 was introduced and excited by plasma 5 or ultraviolet light 6. The generated active molecules or active atoms etch the silicon substrate or the oxide film and react with the contamination. Specifically, the following treatment was performed, and the change in the amount of contamination was measured. Note that the processing time is 3 hours for the etching amount.
The value is about 00 ° and varies depending on each experiment.

The mixed gas of O ₂ + NF ₃ + Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 300 ° C.

Plasma is applied to a mixed gas of O ₂ + CF ₄ + Cl ₂ . Wafer temperature about 300 ° C.

A plasma is applied to a gas mixture of O ₂ + SF ₆ + Cl ₂ and irradiated with ultraviolet light. Wafer temperature about 300
° C.

The Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 300 ° C.

A plasma is applied to the gas mixture of O ₂ + NF ₃ . Wafer temperature about 300 ° C.

Plasma is applied to a mixed gas of O ₂ + CF ₄ . Wafer temperature about 300 ° C.

Plasma is applied to the gas mixture of O ₂ + SF ₆ . Wafer temperature about 300 ° C.

The mixed gas of O ₃ + NF ₃ is irradiated with ultraviolet light. Wafer temperature about 300 ° C.

A plasma is applied to O ₂ . Wafer temperature about 300 ° C.

Among the above processes, the wafer is heated in O ₂ to oxidize the wafer surface, the fluorine gas is excited by plasma or ultraviolet light to etch the oxide film, and Cl ₂ is plasma or It is excited by ultraviolet light, reacts with metal contamination, and is converted into a substance with a high vapor pressure and removed. What is shown here is merely an example, and the heating temperature, the combination of the used gases, and the like are not limited to those described above. Or, it is a comparative example according to the prior art.

Are for heating the wafer in O ₂ to oxidize the wafer surface, exciting a fluorine-based gas using plasma to etch the oxide film, exciting O ₂ with plasma or emitting O ₃ with ultraviolet light. Excitation and react with organic contaminants to remove high-pressure substances. What is shown here is merely an example, and the heating temperature, the combination of the used gases, and the like are not limited to those described above. Is a comparative example according to the prior art.

Table 3 shows the change in the amount of contamination when the above treatment was applied to each contamination.

[0059]

[Table 3]

It can be seen that both metal contamination and organic matter contamination are significantly reduced as compared with the comparative example. (Example 4) Contamination was caused using the wafer (1) shown in the above-mentioned Example 1 in which a thermal oxide film was not formed, and the following treatment was performed to measure the change in the amount of contamination. The processing time is set to a value at which the etching amount is about 300 °, and differs depending on each experiment.

Ultraviolet light is irradiated while introducing O ₂ , NF ₃ , and Cl ₂ in order every 5 seconds. Wafer temperature about 300
° C.

The plasma is applied while introducing O ₂ , CF ₄ , and Cl ₂ sequentially every 5 seconds. Wafer temperature about 300
° C.

Plasma is applied while introducing O ₂ , SF ₆ , and Cl ₂ sequentially every 5 seconds, and ultraviolet light is irradiated. Wafer temperature about 300 ° C.

The Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 300 ° C.

Plasma is applied while introducing O ₂ and NF ₃ alternately every 5 seconds. Wafer temperature about 300 ° C.

Plasma is applied while introducing O ₂ and CF ₄ alternately every 5 seconds. Wafer temperature about 300 ° C.

The plasma is applied while introducing O ₂ and SF ₆ alternately every 5 seconds. Wafer temperature about 300 ° C.

A plasma is applied to O ₂ . Wafer temperature about 300 ° C.

The above description is merely an example, and the introduction interval, the heating temperature, the combination of the used gases, and the like are not limited to those described above. Since a halogen-based gas requires a longer time to exhaust gas than an oxygen gas or the like, a gas introduction stop time of several seconds after the introduction of the halogen-based gas may be provided. , Are comparative examples according to the prior art.

Table 4 shows the change in the amount of contamination when the above treatment was applied to each contamination.

[0071]

[Table 4]

It can be seen that both metal contamination and organic matter contamination are significantly reduced as compared with the comparative example. (Example 5) Using the wafer (1) shown in Example 1 above on which a thermal oxide film was formed, the following treatment was performed, and the change in the amount of contamination was measured. Note that the processing time is such that the etching amount is 300 mm.
It is a value that becomes a degree and varies depending on each experiment.

Ultraviolet light is irradiated while introducing NF ₃ and Cl ₂ alternately every 5 seconds. Wafer temperature about 150 ° C.

Plasma is applied while introducing CF ₄ and Cl ₂ alternately every 5 seconds. Wafer temperature about 150 ° C.

Plasma is applied while SF ₆ and Cl ₂ are alternately introduced every 5 seconds, and ultraviolet light is irradiated. Wafer temperature about 150 ° C.

The Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 150 ° C.

The plasma is applied while introducing O ₂ and NF ₃ alternately every 5 seconds. Wafer temperature about 150 ° C.

Plasma is applied while introducing O ₂ and CF ₄ alternately every 5 seconds. Wafer temperature about 150 ° C.

The plasma is applied while introducing O ₂ and SF ₆ alternately every 5 seconds. Wafer temperature about 150 ° C.

Ultraviolet light is irradiated while introducing O ₃ and NF ₃ alternately every 5 seconds. Wafer temperature about 150 ° C.

A plasma is applied to O ₂ . Wafer temperature about 150 ° C.

The above description is merely an example, and the introduction interval, the heating temperature, the combination of the gases used, and the like are not limited to those described above. Is a comparative example according to the prior art.

Table 5 shows the change in the amount of contamination when the above treatment was applied to each contamination.

[0084]

[Table 5]

It can be seen that both metal contamination and organic matter contamination are significantly reduced as compared with the comparative example. (Example 6) The case where contamination was diffused in the substrate or in the film before cleaning was examined. First, a method for producing a contaminated wafer will be described. Contamination by metal ions is performed by immersing the wafer in an aqueous solution to which a predetermined amount of a standard reagent for atomic absorption of Ni, Fe, or Cu is added for a certain period of time, followed by washing with water,
It is performed by drying. The amount of metal contamination on the wafer is measured in advance by total reflection X-ray fluorescence. Next, the contamination is diffused by the following two methods.

(1) Ni: 500 ° C., 10 minutes, Fe, C
u is heated at 200 ° C. for 10 minutes to diffuse contamination into the substrate.

(2) Ni: 500 ° C., 10 minutes, Fe, C
u forms a thermal oxide film at 200 ° C. for 10 minutes in an oxygen atmosphere and diffuses contamination into the film. Organic contamination is performed by immersing the wafer in an aqueous solution to which a predetermined amount of a surfactant (triethanolamine dodecyl sulfate) is added, followed by washing with water and drying. The surface contamination amount is measured in advance by Auger electron spectroscopy. Next, the contamination is diffused by the following two methods.

(1) Heat at 900 ° C. for 10 minutes to diffuse contamination into the substrate.

(2) A thermal oxide film is formed at 900 ° C. for 10 minutes in an oxygen atmosphere to diffuse contamination into the film.

Using the wafer prepared in the above (1) on which no thermal oxide film was formed, the following treatment was performed, and the change in the amount of contamination was measured.

The mixed gas of O ₂ + NF ₃ + Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 600 ° C.

Plasma is applied to a mixed gas of O ₂ + CF ₄ + Cl ₂ . Wafer temperature about 600 ° C.

Plasma is applied to a gas mixture of O ₂ + SF ₆ + Cl ₂ and ultraviolet light is irradiated. Wafer temperature about 600
° C.

Irradiate Cl ₂ with ultraviolet light. Wafer temperature about 300 ° C.

A plasma is applied to the gas mixture of O ₂ + NF ₃ . Wafer temperature about 600 ° C.

Plasma is applied to a mixed gas of O ₂ + CF ₄ . Wafer temperature about 600 ° C.

A plasma is applied to the gas mixture of O ₂ + SF ₆ . Wafer temperature about 600 ° C.

A plasma is applied to O ₂ . Wafer temperature about 300 ° C.

In the above processes, the wafer is heated to about 600 ° C. in O ₂ to oxidize the wafer surface, and a fluorine-based gas is excited by using plasma or ultraviolet light to etch the oxide film, ₂ is excited by plasma or ultraviolet light, reacts with metal contamination, and is converted into a substance with a high vapor pressure and removed. Therefore, the heating temperature, the combination of the gases used, and the like are not limited to those described above. Or, it is a comparative example according to the prior art.

Are heated to about 600 ° C. in O ₂ to oxidize the wafer surface, to excite fluorine-based gas using plasma to etch an oxide film, and to excite O ₂ with plasma. It reacts with organic contaminants and removes them by converting them into substances with high vapor pressure. Therefore, the heating temperature, the combination of the gases used, and the like are not limited to those described above. Or, it is a comparative example according to the prior art.

Table 6 shows the change in the amount of contamination when the above treatment was applied to each contamination.

[0102]

[Table 6]

It can be seen that both metal contamination and organic matter contamination are significantly reduced as compared with the comparative example. (Example 7) The following processing was performed using the wafer on which the thermal oxide film shown in (2) was formed in Example 6 described above, and the change in the amount of contamination was measured.

The gas mixture of NF ₃ + Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 300 ° C.

Plasma is applied to a mixed gas of CF ₄ + Cl ₂ . Wafer temperature about 300 ° C.

A plasma is applied to a mixed gas of SF ₆ + Cl ₂ and irradiated with ultraviolet light. Wafer temperature about 300 ° C.

The Cl ₂ is irradiated with ultraviolet light. Wafer temperature about 300 ° C.

A plasma is applied to the gas mixture of O ₂ + NF ₃ . Wafer temperature about 300 ° C.

A plasma is applied to the gas mixture of O ₂ + CF ₄ . Wafer temperature about 300 ° C.

A plasma is applied to the gas mixture of O ₂ + SF ₆ . Wafer temperature about 300 ° C.

The mixed gas of O ₃ + NF ₃ is irradiated with ultraviolet light. Wafer temperature about 300 ° C.

The plasma is applied to O ₂ . Wafer temperature about 300 ° C.

In the above processes, the oxide film is etched by exciting the fluorine-based gas using plasma or ultraviolet light, and the Cl ₂ is excited by plasma or ultraviolet light to react with metal contamination to increase the vapor pressure. It is changed to a substance and removed. Therefore, the heating temperature, the combination of the gases used, and the like are not limited to those described above. Or, it is a comparative example according to the prior art.

[0114] ~ is a fluorine-based gas to etch the oxide film is excited by a plasma or ultraviolet light, O ₂
Is excited by plasma or O ₃ is excited by ultraviolet light to react with organic contaminants and remove them by converting them into substances having a high vapor pressure. Therefore, the heating temperature, the combination of the gases used, and the like are not limited to those described above. Is a comparative example according to the prior art.

Table 7 shows the change in the amount of contamination when the above treatment was applied to each contamination.

[0116]

[Table 7]

It can be seen that both metal contamination and organic matter contamination are significantly reduced as compared with the comparative example. The results of Examples 6 and 7 indicate that the present invention can also effectively remove contamination that diffuses in the substrate or in the film before cleaning.

(Embodiment 8) A CV is applied to a Si wafer (without a thermal oxide film) contaminated with an organic substance by the method shown in Embodiment 1.
After forming an oxide film (SiO ₂ film) using Method D, a hole 3 was formed by lithography as shown in FIG.

After processing according to the method described in Example 1, a poly-Si film 7 was formed by the CVD method. The contact resistance was reduced to ２〜 to し て as compared with a film formed by processing according to the method shown as a comparative example in Example 1. In other words, a semiconductor device with good characteristics can be manufactured by the integrated cleaning and film forming process according to the present invention.

(Example 9) A Si wafer (without a thermal oxide film) contaminated with Fe by the method shown in Example 1 was treated by the method shown in Example 1 and then subjected to 850 ° C in an oxygen atmosphere. For 40 minutes to form a thermal oxide film 2 as shown in FIG.

After annealing the obtained wafer in hydrogen, the lifetime was measured. In the case of forming a thermal oxide film by processing according to the method shown as a comparative example in Example 1, the lifetime value was 100 to 150 μs, whereas the one made in this example was as good as 160 to 210 μs. was gotten.

Example 10 A Si wafer (without a thermal oxide film) contaminated with Fe by the method shown in Example 1 was subjected to element separation as shown in FIG. After the treatment, the substrate was treated at 850 ° C. for 40 minutes in an oxygen atmosphere to form a thermal oxide film 2.

Further, a poly-Si film 7 was formed by a CVD method, processed by lithography, and then a dopant was introduced by ion implantation. As a result of activating the dopants and attaching electrodes, and evaluating the MOS breakdown characteristics, the average value of the characteristics was improved by about 20% as compared with that treated by the method shown as a comparative example in Example 1.

(Embodiment 11) FIG. 6 shows an example of a cleaning apparatus according to the present invention.

The sample wafer 11 is set in the vacuum chamber 10. The gas introduced from the gas inlet 17 is turned into plasma by the cavity 13, and the gas introduced from the gas inlet 18 is excited by the ultraviolet lamp 15 to clean the surface of the sample 11. Examples of the type of gas, the excitation method, and the like include those described in the above embodiment.

In FIG. 6, reference numeral 12 denotes a sample heating table,
14 is a microwave power supply, 16 is a quartz window, and 19 is a vacuum exhaust device.

(Embodiment 12) FIG. 7 shows an example of an integrated cleaning and film forming apparatus according to the present invention.

The cleaning device 21 has the structure shown in the eleventh embodiment and is equipped with a monitor 24. The film forming device 22 is a CV
A poly-Si film is formed by the method D.
A silane-based gas is introduced from 6 and the sample 11 is heated 2
The film formation is carried out by heating with the step (5). The integrated cleaning and film forming apparatus shown here has a transfer system that enables the movement of the sample wafer 11 between the sample introduction chamber 20, the cleaning chamber 21, and the film formation chamber 22 without breaking the vacuum.

In FIG. 7, reference numeral 12 denotes a sample heating table,
19 is a vacuum exhaust device, and 23 is a gate valve.

[0130]

According to the present invention, metal contamination on a wafer,
Since organic contamination can be removed, the yield of electronic components such as semiconductor devices can be increased, and the above-mentioned products can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle of the present invention.

FIG. 2 is a diagram showing the results of one example of the present invention.

FIG. 3 is a diagram showing one embodiment of the present invention.

FIG. 4 is a diagram showing one embodiment of the present invention.

FIG. 5 is a diagram showing one embodiment of the present invention.

FIG. 6 is a diagram showing an example of the cleaning device of the present invention.

FIG. 7 is a diagram showing an example of an integrated cleaning and film forming apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Si substrate, 2 ... oxide film, 3 ... hole part, 4 ... cleaning gas 5
... plasma, 6 ... ultraviolet light, 7 ... poly Si film, 8 ... oxide film for element isolation, 9 ... active region into which dopant is injected, 10 ... vacuum chamber, 11 ... sample wafer, 12 ... sample heating table, 13 ... cavity, 14 ... microwave power supply,
15 ... UV lamp, 16 ... Quartz window, 17 ... Gas introduction system
(1), 18: gas introduction system (2), 19: vacuum exhaust device, 20
... Sample introduction chamber, 21 ... Cleaning 8 devices, 22 ... Film forming device, 2
3 gate valve, 24 monitor, 25 heating lamp, 26 gas introduction system (3).

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Tomioka 3-16-16 Shinmachi, Ome-shi, Tokyo F-term in the Hitachi, Ltd. Device Development Center Co., Ltd. 3B116 AA03 AB01 BB82 BB89 BC01 CC05 5F004 AA14 BB05 CA04 DA01 DA04 DA17 DA18 DA26 DA27 DB03 EA28 FA07

Claims (13)

[Claims] 1. A method for removing contamination, wherein means for etching a surface oxide film or the like and means for reacting with metal contamination and changing it to a substance having a high vapor pressure are used simultaneously, alternately or periodically. 2. A method for removing contamination, wherein means for etching a surface oxide film and the like and means for reacting with organic contaminants and changing them to a substance having a high vapor pressure are used simultaneously, alternately or periodically. 3. A means for oxidizing a wafer surface, a means for etching a formed oxide film, and a means for reacting with metal contamination to change to a substance having a high vapor pressure, simultaneously, alternately or periodically. Decontamination method. 4. A means for oxidizing a wafer surface, a means for etching a formed oxide film, and a means for reacting with organic contaminants to change to a substance having a high vapor pressure, simultaneously, alternately or periodically. Decontamination method. 5. The method according to claim 3, wherein the etching amount of the surface oxide film on the wafer is 50 ° or more. 6. The method according to claim 3, wherein the means for etching the wafer surface oxide film comprises applying plasma or irradiating ultraviolet light to a fluorine-based gas. 7. The method according to claim 1, wherein the means for reacting with the metal contamination and changing the substance into a substance having a high vapor pressure has a vapor pressure of the substance at room temperature of 10 to ⁵ Pa or more. Pollution removal method. 8. The contamination according to claim 1, wherein the means for reacting with the metal contamination and changing the substance into a substance having a high vapor pressure is to apply plasma to a chlorine-based gas, or to irradiate or heat ultraviolet light. Removal method. 9. The method according to claim 2, wherein the means for reacting with the organic substance contamination and changing the substance into a substance having a high vapor pressure includes applying plasma to oxygen gas or ozone gas, or irradiating the ozone gas with ultraviolet light. The decontamination method described. 10. A continuous cleaning and film forming method, wherein a film is formed by a CVD method, a sputtering method, or the like, successively to the contamination removing method according to claim 1. 11. A cleaning and thermal oxidation integrated processing method, wherein a gate oxide film or the like is formed by performing thermal oxidation continuously to the contamination removal method according to claim 1. 12. A method according to claim 1, wherein thermal oxidation is performed to form a gate oxide film and the like, and a gate electrode and the like are formed by CVD, sputtering, or the like. Cleaning, thermal oxidation, film forming integrated processing method. 13. The processing method according to claim 10, wherein switching to film formation or the like is performed by monitoring cleanliness.