Method of plasma etching of dielectric layers of sic-si3n4

 

(57) Abstract:

Usage: in microelectronics in the manufacture of integrated circuits at the stage of plasma etching, passivating coatings. The technical result of the invention is to eliminate the formation of fluorocarbon films, which leads to higher quality products. The invention consists in carrying out the process of plasma etching a two-layer pestiviruses coating of SiC-Si3N4in the gas mixture CF4-O2-Ar ratio of components in a three-dimensional parts (20-40) : 1 : 40-60), feeding RF power to the electrode-polictial, with subsequent cleaning of the surface in the gas mixture SF6-Ar, with the ratio of components in the bulk part 1:(40-60) in a single cycle without resultant deposition rates fluorocarbon polymer film on the surface of the semiconductor wafer.

The invention relates to the field of microelectronics, in particular to the technology of IP to plasma etching processes.

The process of plasma etching of layers of SiC-Si3N4is used during etching pestiviruses dielectric for dissection pads in the manufacture of thermocontrol.

Known methods for the SiC (100) Thin Films in SF6. J. Of Electrochem. Soc., Vol. 136, No. 2, February 1989, p. 491-494. It consists in the fact that the SiC layer is etched in the plasma of SF6at a frequency of 13.56 MHz, power density 0,235 W/cm2and a pressure of 50...200 mtorr.

The disadvantage of this method is the difficulty of vytravlivaetsya SiC grains with crystallographic orientation (100). When the etching these grains are formed pyramidal residues, which very slowly durablility.

Known another method of etching a layer of SiC, as described in the Federal Republic of Germany patent DE 36033725 A1, declared 06.02.1986, published 13.08.1987,, H 01 L 21/308, which is plasma etching of the SiC layer in a mixture of CF4-O2containing at least 40 parts by volume OF2at a frequency of 13.56 MHz, a power density of 0.6 W/cm2, pressure 23...25 PA. The disadvantage of this method is the low selectivity etching of SiC to the photoresist. In fact, the photoresist is etched several times faster than SiC, which does not allow to use MDF for etching fairly thick SiC layers.

The known method of plasma etching a layer of Si3N4described in the book "Plasma technology in the manufacture of VLSI", edited by N. Inspirace and D. brown, Moscow, "Mir", 1987, page 181. It consists in etching the layer of Si3N3N4. When the etching of the multilayer structures of isotropic etching of Si3N4leads to potrawy under the overlying layer, the appearance of the overhanging edges of the overlying layer, followed by deposition of metal will lead to breakage on the ledge.

Another method of etching Si3N4described in U.S. patent 4820378, MKI 4 44 1/22, published 04.11.1989, is the etching of Si3N4plasma SF6-He at low pressure. The disadvantage of this method is the low etching rate.

Closest to the proposed invention, the technical solution is described in the flow chart of the enterprise JSC "RIM and C-d Micron (, Zelenograd) 6.60252. 00009 approved 17.09.1999, He is a two-stage plasma-chemical etching of the layers of SiC-Si3N4in the plasma of CF4-O2-N2when the volumetric ratio of 6:1:7,5, a pressure of 30 PA and a power of the first stage 1 kW, and the second 0,6 kW (collective processing 10 plates).

This method allows in a single cycle to successively etch the SiC layer (0,3...0,4 μm) and a layer of Si3N4(0,3...0,4 µm) to Al (area of contact Windows and pads), receiving the sloping profile of the Loya SiC, which, without interfering with the etching of the layer of Si3N4that sags below and to the end of the process remains on the surface of the wafer (the content of C and F at level 1...4 at. % measured using the Auger electron spectrometry).

The problem to which this invention is directed, is the achievement of the technical result consists in the elimination of education fluorocarbon polymer film, contaminating the wafer during the etching process, resulting in higher quality products.

The problem is solved in the way, including plasma etching of dielectric layers of SiC-Si3N4deposited on a semiconductor wafer, through the photoresistive mask in the gas mixture CF4-O2Is argon with a volumetric ratio of the components(20...40):1:(40...60) feeding RF power to the electrode-polictial and then cleaned the surface of the wafer in the plasma gas mixture of SF6-Ar with a volumetric ratio of component 1:(40...60).

This set of features allows you to achieve the technical result consists in suppressing the formation of fluorocarbon polymer film during the etching of these layers and the removal of this film plates in a single C is s practical use of the invention.

Example 1. A silicon wafer formed with the elements of thermocrete, on which is applied a layer of Si3N4(0.4 µm) and the SiC layer (0.3 μm) formed on the surface of the SiC photoresistive mask (photoresist SP-15 with a thickness of 2.0 μm), tanned at a temperature of 200oC for 20 minutes, were processed at the facility GIR-260 in the plasma of CF4-O2Is argon with a volumetric ratio of 30:1:50, at a pressure of 60 PA, RF power 320 W for 220 seconds (a series of two reactors at 110 seconds), then in the second reactor plasma SF6-AG in the volumetric ratio 1: 50, at a pressure of 60 PA, RF power of 100 W for 20 seconds. In the both layers potraviny to Al, control of surface cleanliness Al method Auger spectrometry any residue fluorocarbon polymer film on the surface of the plate (after plasma removal of photoresist) is not found (the content of C and F on the background level of 0.1 at. %).

Example 2. Plate as in example 1, but with a layer of Si3N4(0.3 μm) and a layer of SiC (0.4 µm) were processed in the same mode over 260 seconds 130 seconds in each reactor). The result is the same as in example 1.

Method of plasma etching of dial the e of these layers through the photoresistive mask in the plasma of a mixture of CF4-O2-AG at a ratio of mixture components in a three-dimensional parts(20 - 40): 1: (40 - 60) accordingly, by applying RF power to the electrode-polictial, and the subsequent cleaning of the surface of the wafer in the plasma of SF6-AG in a ratio of components in the bulk part 1: (40 - 60), respectively.

 

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The invention relates to microelectronics, technology IP high degree of integration, the processes of dry plasma etching

The invention relates to the field of plasma chemistry and can be used in the microelectronics industry in the manufacture of integrated circuits and discrete semiconductor etching and deposition of materials and growing your own dielectrics on semiconductors and metals

Device for locking // 2133521

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for purifying octafluorocyclobutane. Method is carried out by interaction of crude octafluorocyclobutane containing impurities with the impurity-decomposing agent at increased temperature and then with adsorbent that is able to eliminate indicated impurities up to the content less 0.0001 wt.-% from the mentioned crude octafluorocyclobutane. Impurity-decomposing agent comprises ferric (III) oxide and compound of alkaline-earth metal in the amount from 5 to 40 wt.-% of ferric oxide and from 60 to 95 wt.-% of compound of alkaline-earth metal as measured for the complete mass of the impurity-decomposing agent. Ferric (III) oxide represents γ-form of iron hydroxyoxide and/or γ-form of ferric (III) oxide. Impurity represents at least one fluorocarbon taken among the group consisting of 2-chloro-1,1,1,2,3,3,3-heptafluoropropane, 1-chloro-1,1,2,2,3,3,3-heptafluoropropane, 1-chloro-1,1,2,2,3,3,3-heptafluoropropane, 1-chloro-1,2,2,2-tetrafluoroethane, 1-chloro-1,1,2,2-tetrafluoroethane, 1,2-dichloro-1,1,2,2-tetrafluoroethane, hexafluoropropene and 1H-heptafluoropropane. Adsorbent represents at least one of representatives taken among the group including activated carbon, carbon molecular sieves and activated coal. Crude octafluorocyclobutane interacts with the mentioned impurity-decomposing agent at temperature from 250oC to 380oC. Invention proposes gas, etching gas and purifying gas including octafluorocyclobutane with purity degree 99.9999 wt.-% and above and comprising fluorocarbon impurity in the concentration less 0.0001 wt.-%. Invention provides enhancing purity of octafluorocyclobutane.

EFFECT: improved purifying method.

26 cl, 13 tbl, 10 ex

FIELD: organic chemistry, chemical technology.

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