CN1592798A - Cleaning gas for semiconductor production equipment and cleaning method using the gas - Google Patents

Abstract

This invention provides a cleaning gas for removing deposits in equipment used to manufacture semiconductors or liquid crystals, comprising fluorine gas containing 1 vol% or less oxygen and/or oxygen-containing compounds. The cleaning gas of this invention enables efficient semiconductor device manufacturing processes, ensuring high etching rates, high cleaning efficiency, and an excellent performance-price ratio.

Description

Cleaning gas for semiconductor manufacturing equipment and cleaning method using the same

Cross References to Related Applications

This application is filed under 35 U.S.C. Chapter 111(a) and requires the U.S. Provisional Application Serial Number filed June 27, 2002 pursuant to 35 U.S.C. Chapter 119(e)(1) and 35 U.S.C. Chapter 111(a) Priority of No. 60/391,622.

technical field

The present invention relates to a cleaning gas for equipment for manufacturing semiconductors or TFT (Thin Film Transistor) liquid crystal devices, and a cleaning method using the gas, wherein accumulation in the film is formed when forming a film or etching silicon, silicon nitride, silicon oxide, tungsten, etc. Unnecessary deposits in equipment or etching equipment are to be removed, and also relates to a method of manufacturing a semiconductor device including a cleaning step using a cleaning gas.

Background technique

In film forming equipment or etching equipment for manufacturing semiconductors or TFT liquid crystal devices, deposits accumulated in the film forming equipment or etching equipment when forming a film or etching silicon, silicon nitride, silicon oxide, tungsten, etc. cause particles to be generated and Fabrication of good films is hindered, therefore, these deposits must be removed when necessary.

Deposits in semiconductor manufacturing _equipment are therefore removed by plasma etching the deposits excited by fluorine-type etching gases such as _NF3 , _CF4 , and _C2F6 . However, the method using NF ₃ has a problem that NF ₃ is expensive, and the method using perfluorocarbons such as CF ₄ and C ₂ F ₆ has problems of low etching rate and low cleaning efficiency. In addition, an etching method using an etching gas such as perfluorocarbon releases a large amount of unreacted gas, requires a post-process to eliminate polluting emissions, and imposes a heavy burden on the environment by releasing greenhouse gas.

On the other hand, as a technique to increase _the cleaning efficiency, a method of adding _O2 to perfluorocarbons such as _CF4 and _C2F6 is employed, however, it is also known that adding _O2 in excess will negatively Reduced cleaning efficiency. It is hypothesized that the addition of _O2 has the effect of (1) reacting with carbon or sulfur separated during excitation to generate _COx or _SOx , and (2) inhibiting the formation and reformation of CC bonds or SS bonds to easily release fluorine. Although the interaction between F and O is weak compared with the interaction between C and O or S and O, excess oxygen (O) accelerates the activity reduction of F groups.

The advantage of using _F2 gas as the cleaning gas is that the process of eliminating polluting emissions is easy. In terms of energy required, conventional cleaning methods using gases such as perfluorocarbons and _NF3 consume a large amount of energy in the process of eliminating large amounts of unreacted exhaust gases, whereas cleaning methods using _F2 can easily It pays to eliminate the high reactivity of polluting emissions from commonly used conventional processes.

Since the process of removing deposits is based on the reaction between fluorine and deposits, if the gas introduced is pure fluorine, theoretically, the cleaning efficiency will be the highest.

However, currently commercially available fluorine gas has very low purity, and impurities such as HF, O ₂ , N ₂ , CO ₂ , H ₂ O, CF ₄ and SF ₆ are contained therein. O ₂ , CO ₂ and H ₂ O can negatively affect cleaning processes using F ₂ gas, although HF can be removed relatively easily by absorption operations, N ₂ , CF ₄ and SF ₆ that can be used as diluent or etching gases are Cleaning processes using F ₂ gas have little negative impact.

Contents of the invention

It is under these circumstances that the present invention is formed. Accordingly, an object of the present invention is to provide a cleaning gas and a cleaning method using the gas, which can ensure a high etching rate, high cleaning efficiency, and excellent cost performance. Furthermore, another object of the present invention is to provide a method of manufacturing a semiconductor device.

After extensive research to solve the above-introduced problems, the present inventors found that a cleaning gas including fluorine and having an extremely low content of oxygen and/or oxygen-containing compounds increases etching rate and improves cleaning efficiency, thereby completing the present invention.

That is, as described in (1) and (16) below, the present invention relates to a cleaning gas and a cleaning method, and a method of manufacturing a semiconductor device.

(1) Cleaning gas for removing deposits in equipment for manufacturing semiconductors or liquid crystals, including fluorine gas containing 1 vol% or less of oxygen and/or oxygen-containing compounds.

(2) The cleaning gas described in (1) above, wherein the content of oxygen and/or oxygen-containing compounds contained in the fluorine gas is 0.5 vol% or less.

(3) The cleaning gas described in (2) above, wherein the content of oxygen and/or oxygen-containing compounds contained in the fluorine gas is 0.1 vol% or less.

(4) The cleaning gas described in any one of (1) to (3) above, wherein the purity of the fluorine gas is 99 vol% or more.

(5) The cleaning gas described in (4) above, wherein the purity of the fluorine gas is 99.5 vol% or more.

(6) The cleaning gas described in any one of (1) to (3) above, wherein the oxygen-containing compound is selected from NO, N ₂ O, NO ₂ , CO, CO ₂ , H ₂ O, OF ₂ , O ₂ F ₂ and at least one compound from the group consisting of O ₃ F ₂ .

(7) The cleaning gas described in (6) above, wherein the oxygen-containing compound is at least one compound selected from the group consisting of CO, CO ₂ and H ₂ O.

(8) The cleaning gas described in any one of (1) to (7) above includes at least one diluent gas selected from the group consisting of He, Ar, N ₂ , Ne, Kr and Xe.

(9) The cleaning gas described in (8) above, comprising at least one diluent gas selected from the group consisting of He, Ar and _N2 .

(10) A method of cleaning semiconductor or liquid crystal device manufacturing equipment using the cleaning gas described in any one of (1) to (9) above.

(11) The cleaning method described in (10) above, wherein the cleaning gas described in any one of (1) to (9) above is activated to generate plasma in which deposits in semiconductor manufacturing equipment are removed.

(12) The cleaning method described in (11) above, wherein the activation source for plasma is microwaves.

(13) The cleaning method described in (10) above, wherein the cleaning gas is used at a temperature in the range of 50 to 500°C.

(14) The cleaning method described in (10) above, wherein the cleaning gas is used in a temperature range of 200 to 500° C. in a plasma-free system.

(15) A method of manufacturing a semiconductor device comprising a cleaning step using the cleaning gas described in any one of (1) to (9) above and a decomposition step of decomposing fluorine-containing compound gas discharged from the cleaning step.

(16) The method of manufacturing a semiconductor device described in (15) above, wherein the fluorine compound is at least one compound selected from the group consisting of SiF ₄ , HF, CF ₄ , NF ₃ and WF ₆ .

Description of drawings

FIG. 1 schematically shows an etching apparatus using the cleaning gas of the present invention.

Detailed ways

The present invention will be described in detail below.

The cleaning gas used for the semiconductor or liquid crystal device manufacturing equipment of the present invention includes fluorine gas containing 1 vol% or less of oxygen and/or oxygen-containing compounds.

In the cleaning gas used for semiconductor manufacturing equipment, the content of oxygen and/or oxygen-containing compounds contained in fluorine gas is preferably 0.5 vol% or less, more preferably 0.1 vol% or less. If the content of oxygen and/or oxygen-containing compounds in the fluorine gas exceeds 1 vol%, the cleaning efficiency will undesirably decrease.

The oxygen-containing compound is, for example, at least one compound selected from the group consisting of NO, N ₂ O, NO ₂ , CO, CO ₂ , H ₂ O, OF ₂ , O ₂ F ₂ and O ₃ F ₂ . The cleaning gas is characterized by including fluorine gas containing 1 vol% or less of oxygen and/or oxygen-containing compounds. The oxygen-containing compound may be one or more compounds selected from the group consisting of CO, CO ₂ and H ₂ O.

The purity of fluorine gas determined by eliminating oxygen and/or oxygen-containing compounds contained therein as impurities is preferably 99 vol% or more, more preferably 99.5 vol% or more. Additionally, while the cleaning gas of the present invention includes fluorine gas containing 1 vol% or less oxygen and/or oxygenates, preferably without diluting the fluorine gas, the fluorine gas can be diluted if some cleaning conditions require it. The gas used to dilute the fluorine gas is preferably at least one diluent gas selected from the group consisting of He, Ar, N ₂ , Ne, Kr and Xe, more preferably selected from the group consisting of He, Ar and N ₂ at least one diluent gas.

When cleaning semiconductor manufacturing equipment using the cleaning gas of the present invention, the gas can be used under plasma conditions or under plasma-free conditions.

When a gas is used under plasma conditions, the excitation source is not particularly limited as long as plasma is excited from the cleaning gas of the present invention, but a microwave excitation source is preferred because good cleaning efficiency can be obtained. Furthermore, when using the cleaning gas of the present invention, the temperature and pressure are not particularly limited as long as plasma can be generated, but the temperature range is preferably 50 to 500° C., and the pressure range is preferably 1 to 500 Pa.

When in a plasma-free condition, a cleaning gas is introduced into the chamber, the internal pressure of the chamber is preferably set at 1 to 500 Pa, and the interior of the chamber and at least a part of or both of the cleaning gas are heated at 200 to 500° C. to activate the cleaning gas. The semiconductor fabrication equipment is then cleaned by etching and removing the deposits from the chamber and other areas where the deposits have accumulated.

In the cleaning gas used for the semiconductor manufacturing equipment of the present invention,

(1) _F2 gas that can dissociate at a lower energy level and generate active species is contained in the gas, and

(2) Oxygen and/or oxygen-containing compounds contained therein have a negative influence on the generation and maintenance of fluorine radicals, and their content is minimized. Through these features, the present invention exhibits more advantageous effects compared with the conventional use of NF ₃ gas. Compared to NF _gas , F dissociates at low energy levels and complete _dissociation , producing only F radicals. Therefore, since only active species are present in the system when cleaning is performed, the reaction efficiency with the deposits accumulated therein is extremely high.

FIG. 1 shows an example of an etching apparatus using the cleaning gas of the present invention. The cleaning gas is introduced into the chamber 1 set at a constant temperature through the cleaning gas inlet 6, and at this time, the gas is excited by the microwave plasma excitation source to generate plasma. The gas obtained after etching the silicon wafer 2 on the sample stage 3 is exhausted by the dry pump 5, and becomes harmless using a decomposer according to the kind of gas contained therein. In addition, deposits accumulated after etching are effectively removed by repeating the same operation with etching, whereby the chamber can be effectively cleaned.

Next, the manufacturing process for the semiconductor device of the present invention will be described.

As described above, according to the present invention, cleaning of semiconductor manufacturing equipment can be efficiently performed. However, the gas discharged during the cleaning process using the cleaning gas of the present invention contains fluorine compounds such as HF, CF ₄ , SiF ₄ , NF ₃ , and WF ₆ in addition to the F ₂ gas used for cleaning. These compounds containing _F2 , if released into the atmosphere, greatly contribute to global warming due to the fact that they are, or if they decompose, produce acid gases, there is a need to render these compounds completely harmless. The present invention provides a manufacturing process for semiconductor devices comprising a cleaning step of semiconductor manufacturing equipment and a decomposition step of decomposing fluorine-containing compound gas discharged from the decomposition step in the manufacturing process of semiconductor devices.

Cleaning steps for semiconductor manufacturing equipment are performed using the methods described above. In addition, the method used in the decomposition step of decomposing the fluorine-containing compound discharged from the cleaning step is not particularly limited, and the decomposition agent is selected according to the kind of compound contained in the exhaust gas. Preferably hydrogen fluoride is released after stabilization as metal fluoride and carbon is released after decomposition as carbon dioxide.

Best Mode for Carrying Out the Invention

The present invention will be described in more detail below by referring to Examples and Comparative Examples, however, the present invention is not limited to these Examples.

Example 1 to 2

The test device shown in FIG. 1 was adjusted to a device internal pressure of 300 Pa. The cleaning gas having the composition shown in Table 1 was excited by a microwave plasma excitation source of 2.45 GHz and 500 W, and then introduced into the test device to etch the silicon wafer placed in the test device. The etch rate was determined from the volume loss of the silicon wafer after etching and the results are shown in Table 1.

Table 1 example Gas used and mixing ratio (volume %) Etching rate (nm/min) F ₂ O ₂ 2000 1 100 0 2 99 1 1800

It was shown that the _F2 gas containing 1 vol% or less of oxygen showed a considerably high etching rate.

Comparative example 1

The etching rate of each cleaning gas was determined in the same manner as in Example 1 except that the cleaning gas was changed to a gas having the composition shown in Table 2.

Table 2 comparative example Gases used and mixing ratio (volume ratio) Etching rate (nm/min) F ₂ O ₂ 1200 1 95 5

It was shown that the etching rate is significantly reduced when the _F2 gas contains 5 vol% or more of oxygen.

Example 3

Instead of a silicon wafer, a quartz wafer on which deposits of amorphous silicon, silicon nitride, etc. have accumulated is cleaned. The cleaning gas used in Example 1 was excited by a microwave plasma excitation source of 2.45 GHz and 500 W and introduced into a test device adjusted to an internal pressure of 300 Pa, and the quartz plate was cleaned and taken out. From this, it was confirmed that the deposits were completely removed.

Industrial Applicability

The etching rate of the cleaning gas used in the semiconductor manufacturing equipment of the present invention is high, and therefore, efficient cleaning and excellent cost performance can be ensured. According to the cleaning method of semiconductor manufacturing equipment of the present invention, unnecessary deposits accumulated in film forming equipment or etching equipment during film formation or etching of silicon, silicon nitride, silicon oxide, tungsten, etc. can be effectively removed. Furthermore, by using the cleaning step of the cleaning gas of the present invention and the decomposition step of decomposing the fluorine-containing compound gas discharged from the cleaning step, it is possible to make it harmless and efficiently manufacture semiconductor devices.

Claims (16)

CLAIMS 1. A cleaning gas for removing deposits in equipment for manufacturing semiconductors or liquid crystals, comprising fluorine gas containing 1 vol% or less of oxygen and/or oxygen-containing compounds. 2. The cleaning gas according to claim 1, wherein the content of oxygen and/or oxygen-containing compounds contained in the fluorine gas is 0.5 vol% or less. 3. The cleaning gas according to claim 2, wherein the content of oxygen and/or oxygen-containing compounds contained in the fluorine gas is 0.1 vol% or less. 4. The cleaning gas according to any one of claims 1 to 3, wherein the purity of the fluorine gas is 99 vol% or more. 5. The cleaning gas according to claim 4, wherein the purity of the fluorine gas is 99.5 vol% or more. 6. A cleaning gas according to any one of claims 1 to 3, wherein _the oxygenate is selected from the group consisting of NO, _N2O , _NO2 , CO, _CO2 , _H2O , _OF2 , _O2F2 and _O3 At least one compound in the group consisting of _F2 . 7. The cleaning gas according to claim 6, wherein the oxygen-containing compound is at least one compound selected from the group consisting of CO, _CO2 and _H2O . 8. The cleaning gas according to any one of claims 1 to 7, comprising at least one diluent gas selected from the group consisting of He, Ar, _N2 , Ne, Kr and Xe. 9. The cleaning gas according to claim 8, comprising at least one diluent gas selected from the group consisting of He, Ar and _N2 . 10. A method of cleaning semiconductor or liquid crystal device manufacturing equipment using the cleaning gas according to any one of claims 1 to 9. 11. The cleaning method according to claim 10, wherein the cleaning gas described in any one of claims 1 to 9 above is activated to generate plasma in which deposits in semiconductor manufacturing equipment are removed. 12. The cleaning method according to claim 11, wherein the activation source for the plasma is a microwave. 13. The cleaning method according to claim 10, wherein the cleaning gas is used at a temperature in the range of 50 to 500°C. 14. The cleaning method according to claim 10, wherein the cleaning gas is used in a temperature range of 200 to 500° C. in a plasma-free system. 15. A method of manufacturing a semiconductor device comprising a cleaning step using the cleaning gas described in any one of claims 1 to 9 above and a decomposition step of decomposing fluorine-containing compound gas discharged from the cleaning step. 16. The method of manufacturing a semiconductor device according to claim 15, wherein the fluorine compound is at least one compound selected from the group consisting of _SiF4 , HF, _CF4 , _NF3 and _WF6 .