The method of cleaning the surface

 

(57) Abstract:

Usage: microelectronics cleaning the surface of the wafer during fabrication of very large scale integrated circuits. Essence: place the cleaned wafer in a vacuum chamber and treated with the surface of the plate intense jet bioaerosol nitrogen and argon, with the addition of impurity oxygen in the presence of ultraviolet radiation with a wavelength less than 200 nm. The technical result of the invention is to improve the treatment efficiency of organic pollutants surface with smooth terrain. table 1.

The scope of the invention is microelectronics, namely the methods of cleaning the surface of the wafer during fabrication of very large scale integrated circuits (VLSI).

The known method of surface cleaning from mechanical impurities, which consists in processing the surface being cleaned by compressed carbon dioxide - CO2that when extending into the space turns into particles of dry ice and these particles effectively cleans the surface from mechanical particles and organic impurities [1].

However, it is not effectively cleans the surface with a complex profile is the first gas is a good solvent for many organic compounds, including hydrocarbons, and it is difficult to clean.

The disadvantage of this method is that after such surface treatment is not excluded the possibility of contamination by traces of oils contained in the CO2and the carbon dioxide by their chemical nature is contaminating impurity when creating VLSI.

Closest to the proposed invention is a method of cleaning a surface using a cryogenic aerosol, including room cleaned plates in high-purity vacuum chamber and processing the surface of an intense jet of liquefied gases argon and nitrogen at a temperature close to the melting point of argon. When this occurs, the surface treatment spray liquid nitrogen and particulate solid argon, which effectively clean the surface from mechanical impurities, including submicron particles and polymer residues after reactive-ion etching (RIT) [2]. Remote spray with plate particles and polymers are removed from the chamber with aerosol otkaznuyu system. This method is used for surface cleaning of silicon wafers from sub-micron particles, organic sediments and films visockaite, that it is ineffective when cleaning the surface of organic trace contaminants with smooth profile.

The task to be solved by the invention is the achievement of the technical result consists in an additional cleaning of the surface from organic trace contaminants with smooth profile. This technical result is achieved in the method of cleaning the surface, including the location of the cleaned plates in high-purity vacuum chamber and simultaneous treatment of the surface being cleaned intense jet craaaaaazy argon and nitrogen mixed with oxygen and ultraviolet radiation with a wavelength less than 200 nm.

Thus, the distinctive features of the invention are additional processing of the cleaned surface with ultraviolet radiation with a wavelength less than 200 nm with the introduction bioaerosol argon and nitrogen impurities of oxygen.

Listed distinctive features can achieve the technical result.

The process of cleaning the surface is as follows. The cleaned plate is placed in a vacuum chamber and simultaneously process the stream bioaerosol argon and nitrogen with primes and and nitrogen and has energy, sufficient for the destruction of chemical bonds of organic compounds and in the presence of traces of oxygen in quantities do not significantly affect the attenuation of the intensity of the flux of ultraviolet radiation on the treated surface, and for the intensive oxidation of organic compounds. Therefore, this additional processing leads to clean the surface from organic impurities with smooth terrain. The source of ultraviolet radiation can be situated directly in the vacuum chamber, and beyond. In the latter case, the radiation from the source is directed onto the cleaned wafer into the chamber through a window made of transparent to the wavelengths of material, such as sapphire, calcium fluoride, magnesium fluoride. As a source of ultraviolet radiation may be applied excimer laser with a wavelength less than 200 nm, lamp sources of intense ultraviolet radiation with a wavelength less than 200 nm (e.g., dauterive discharge lamp, a mercury low pressure lamp with a quartz envelope), or this ultraviolet radiation can be formed directly in the cell by initiating in the residual gases vysokotrave glass sealed on the surface of the camera above the table.

An example implementation of the method.

Chemically cleaned silicon wafer was applied 1% solution of S1813 photoresist in acetone. Then the plates were dried at 100oWith 1 min on a hot plate. Prepared plates were divided into six groups. The first group of plates was analyzed for the presence of carbon by the method of secondary ion mass spectrometry (Sims). Plates of the second group was placed on a table in a vacuum chamber. The chamber was pumped turbomolecular pump. Then the plate was processed in a spray jet of bioaerosol consisting of drops of liquid nitrogen, mixed with particles of solid argon (10%), with continuous pumping, and the treated area of the plate was analyzed for the presence of carbon by the method of VIMS. Plates of the third group was placed on a table in a vacuum chamber. The chamber was pumped turbomolecular pump. Then the plate was processed in a spray jet of liquid nitrogen with a mixture of argon (10%) and oxygen (1%) under continuous pumping, and the treated area of the plate was analyzed for the presence of carbon by the method of VIMS. Plate of the fourth group were placed on a table in a vacuum chamber. Camera otkazivani power of 350 W and a spray jet of bioaerosol, consisting of drops of liquid nitrogen, mixed with particles of solid argon (10%), with continuous pumping. The treated area of the plate was analyzed for the presence of carbon by the method of VIMS. Plate of the fifth group was placed on a table in a vacuum chamber. The chamber was pumped. Then the Central part of the plates were processed VUV radiation from the deuterium lamp power of 350 W and a spray jet of bioaerosol consisting of drops of liquid nitrogen, mixed with particles of solid argon (10%) and gaseous oxygen (1%), with continuous pumping. The treated area of the plate was analyzed for the presence of carbon by the method of VIMS. In all experiments, the jet of atomizing gas was supplied to the plate surface at an angle close to 45o. The processing time for the VUV radiation and jet bioaerosol was five minutes. Sixth group of plates washed off the traces of photoresist in acetone, subjected to liquid chemical processing in CARO+PAIRS and analyzed in the presence of carbon by the method of VIMS. The main results of the Sims analysis shown in the table. As the wine from the table, the surface of the wafer from the first group covered by the carbon with the relative intensity of the signal at the level of 1017. The first surface. Plates of the second group have a lower concentration of carbon in comparison with plates from the first group (at the level of 1014), about the same concentration of carbon have and plates of the third group. Plate of the fourth group has a much lower concentration of carbon on the surface (relative signal intensity carbon 1010), and the plate of the fifth group have an average concentration of carbon on the surface of the minimum of all the groups of plates, in addition to the plates of the fourth group, i.e. the highest degree of purification.

LITERATURE

1. Similar: Stuart A. Hoenig / Cleaning Surfaces with Dry lce//Compressed Air Magazine, August 1986, p.22-24.

2. Prototype: W. T. McDermott, Ockovic R. C., Wu J. J., Cooper D. W., Snwarz A. , Wolfe H. L. Patent EP 0461476 A2 from 29.05.91, H 01 L 21/306, priority 05.06.90, US 534810.

The method of cleaning the surface including the location of the cleaned wafer in a vacuum chamber and processing the surface of the plate intense jet bioaerosol nitrogen and argon, characterized in that bioaerosol nitrogen and argon is injected admixture of oxygen and subjecting the surface to be cleaned simultaneously with the processing of the stream bioaerosol processing by ultraviolet radiation with a wavelength less than 200 nm.

 

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