TW449824B - Chemical gas etching method for removing nitride hard mask layer in a semiconductor process - Google Patents

Abstract

The present invention discloses a chemical gas etching method for removing nitride hard mask layer in a semiconductor process, which is used particularly for etching silicon nitride. The present invention utilizes the mixed gas of SF6, CHF3, CF4, N2 and Ar to etch the nitride, thereby avoiding a large-angle etching phenomenon in the etching process.

Description

449824 Temple Moon Sun Articles-88118Π? 3 V. Description of the Invention (1) Field of Invention: Horigan is concerned with a hard mask for removing nitrides in semiconductor processes. "Chemical gas etching method" is usually used to etch nitrogen Silicon. 5-2 Background of the Invention: In the semiconductor process, silicon nitride (Si3N4) is traditionally etched by using a silicon nitride etcher (Etcher) in plasma etching mode (Plasma Mode) to etch, or using a reaction Oxide Etcher in RiE Mode for etching. When etching is performed in the semiconductor shallow trench isolation process to define the location of the shallow trench, a mixed trifluoride / carbon tetrafluoride / argon (CHF3 / CF4 / Ar) gas is mainly used as the process. Etching gas. However, the use of a mixture of carbon trifluoride, carbon tetrafluoride and argon as the remaining gas 'when removing the nitride layer 11 (such as silicon nitride) not covered by the photoresist 12' cannot be used A nitride layer with edges perpendicular to the substrate is formed, as shown in FIG. 1A. Generally speaking, the included angle between the edge of the nitride layer 11 and the substrate 10 is about 60 to 70 degrees. Therefore, after the nitride layer Π is used as the hard mask layer to etch the substrate 10 to form a shallow trench and fill the dielectric material to form the shallow trench isolation 13, a shallow trench isolation 13 with an upper cross-sectional area greater than the bottom cross-sectional area will be generated. As shown in the first B diagram. In this way, in the subsequent process of removing the hard mask layer and forming the polycrystalline silicon gate, a polysilicon stringer 14 is produced in a corner adjacent to the shallow trench isolation 13

Page 4 44 9 824 V. Description of the invention (2) Production, as shown in the first C: picture. Especially in the semiconductor line width 0.2 method of gas generation β * tutorial, the shallow trench caused by the edge tilt of this traditional square nitride layer is not serious P ^ f _, and then seriously affect the high requirements of the process In the past ten years or more, it has been compared with the bad corridor of Gaoququ. Since the emergence of the computer with the RAM of the Thundership (RAM), it is due to random memory. Increase the information industry of mr computer hardware. At the same time, it is not only used in »Industry ', it is also generally used in large-scale integrated circuits (VLSI) and very large boxes Undoubtedly, that is, a century later, the process technology of random memory (RAM) still occupies a very important position in the information industry. In the process of random memory, especially in the process of dynamic random memory, with the process technology With the progress of the future, the size of the components in the future will be more and more tend to minimize the atomic size. The line width of the current production line has reached the width of the sub-micron 'such as 0.1 8 microns. At the same time, the goal of manufacturing finished products is also the semiconductor product. As mentioned above, "In order to avoid the phenomenon of large-angle excessive tilt in the etching process during the semiconductor process, and maintain the inclined shape required for shallow trenches, it is necessary to improve and improve the random dynamic memory (DRAM). The need for process technology 'so it is urgent to propose a new process method and structure to improve the above problems' and improve component quality and manufacturing efficiency.

Page 5

449824 __Case No. 8811823 V. Description of the invention (3) 5-3 Purpose and summary of the invention: In view of the above background of the invention, carbon fluoride (CF4) and argon (Ar) are the main ones: fluoride Carbon (thorium), many shortcomings produced by the gas; four gas, as the sulfur (SFs) in the process of the two gases added nitrogen (thorium) and fluorinated main mixture # 刻In the gas, I :::: carbon tetrafluoride and gas are used as the etching gas. * Shows the chemical gas etching method of the semiconductor shallow trench isolation capping layer due to the nitride etching process, which can include: a mixture of a plurality of species, the plurality of gases at least include: hafnium fluoride ... ^ Seed gas sulfide (sf6), carbon trifluoride (CHW, carbon tetrafluoride), nitrogen (N2) and nitrogen (Ar); Provide a substrate, and cover the substrate with a nitride layer Forming a photoresist layer on the nitride layer so as to define the positions of at least two trench isolation regions; and then mixing the etching gas to remove a portion of the nitride layer not covered by the photoresist layer. Of the five gases, sulfur fluoride (SFe) is formulated at a quantitative mixing ratio of one to two percent. Carbon trifluoride (CHF;}) is formulated at a quantitative mixing ratio of one to four percent. And carbon tetrafluoride (CF4) is formulated with a quantitative mixing ratio of 5.7 percent. In addition, nitrogen (N2) was formulated at a quantitative mixing ratio of 5.2 percent. Finally, American Gas (Ar) is formulated with a quantitative mixing ratio of 84.9% to 449824 _ Case No. gi118 3 3 I said a______ 5. Description of the invention (4) According to the method described above, the present invention provides a The method to avoid the excessive angle phenomenon in the narration process. In order to make the above description of the present invention and other objects, features, and advantages noticeable, the preferred embodiments are listed below in conjunction with the accompanying drawings, and detailed descriptions are provided. , Ming: The drawings briefly say that A to C are the etching results of the traditional process; Figures A to C of the second embodiment of the process of the preferred embodiment are schematic diagrams of the present invention; and the second A FIG. 3 to FIG. 3F are printing diagrams of another preferred embodiment of the cross-section + present% AI power of the present invention. Symbols of the main parts of the invention: 10 substrate 11 nitride layer 12 photoresist 13 shallow trench isolation 14 polycrystalline silicon string ^ substrate 〇1 nitride layer

Page 7 4 49 82, 4 __t No. 8811823 V. Description of the invention (5) 22 Photoresistive layer 30 Substrate 31 Silicon nitride layer 32 First-Photoresistor 33 On a 34 Dielectric material 35 Conductor layer 36 Second light Obstacle 5-5 invention detailed gb description: The following is a reference for the construction of the present invention. The preferred methods for these changes will be followed later, although this example does not limit the invention to the use of polysilicon gate t-response and it is obvious that several examples are better than the listed examples. Equivalent changes or modifications within the fence. In addition, all other similar and approximate changes not described above are described. The description of the present invention will first be accompanied by an exemplary structure and the advantages of the present invention will be described later. Β manufacturing will be described with the following examples' but the scope or application of these implementations. Moreover, although the examples are clear, even though the present invention is described by way of example, the present invention is not limited to the specific examples previously listed and described without departing from the spirit disclosed by the present invention. All shall be included in the patent application scope of the present invention for changes or modifications that deviate from the spirit disclosed in the present invention, and shall also be included in the invention. Page 8 _m 88118023 ) " Please within the scope of the patent. At the same time, the scope of the present invention should be interpreted in its broadest definition so as to encompass all modifications and similar structures. The preferred embodiments of the present invention generally use mixed gas as the main etching method. When performing nitride processing such as silicon nitride (Sis), nitrogen is used by using plasma plasma mode (Plasma Mode). Silicon etcher (s "n4 Etcher) etc., etc., to etch silicon nitride (S i3 N4) layer with money.

A preferred embodiment of the present invention is a chemical gas etching method for removing a nitride hard mask layer in a semiconductor process. First, as shown in FIG. 2A, “provide a substrate 20” and cover the substrate with a nitride layer 21; then, as shown in FIG. 2B, a photoresist layer 22 is formed on the nitride layer 21 to define at least two The location of the trench isolation area; finally, a part of the nitride layer 2 not covered by the photoresist layer 22 is removed with a mixed etching gas of sulfur fluoride (SF6), carbon fluoride gas 'IL gas (N2)' and an inert gas.丨, as shown in the second c diagram.

Comparing the second C diagram and the -b diagram, it can be seen that compared with the traditional method, this embodiment can provide a contour of the less inclined nitride layer, that is, a better shallow trench profile can be obtained in this embodiment. And can reduce the degree and possibility of polycrystalline silicon strings. In this preferred embodiment, the etching gas used is as follows; a quantitative nitrogen (n) of 5.2 per 100 knives and a quantitative sulfur fluoride of 2.8 per cent

44982a _ Case No. 8811823_ Year η, τ Five 'invention description (7) ~, added to the quantitative carbon trifluoride (CH !? 3), 5.7 percent quantitative Carbon tetrafluoride (eh) and a mixed inert gas with a quantitative ratio of 84.9% inert gas ^ (such as argon (A r)) are used as the residual gas. Therefore, a total of nitrogen, sulfur fluoride, carbon trifluoride, and carbon tetrafluoride gas are used to perform the chemical etching process. Generally, it is sent in after mixing for the etching process, so it is used to leave nitrides, such as nitrided sand. Generally, when nitrogen is introduced, a nitrogen-containing polymer is generated and formed on the surface of silicon atoms. This nitrogen-containing polymer not only protects the side walls of the shallow trench (Sidewal 1) during the money-etching process, but can also be easily removed after the etching process. Note, however, that excessive nitrogen must not be added to avoid condensing the gas. During the manufacturing process, attention must also be paid to the adjustment of gas flow rate (n0w Rate) and flow rate. Another preferred embodiment of the present invention is the application of the foregoing. This preferred embodiment is a method for forming a shallow trench isolation and a gate electrode. The method includes at least: as shown in the second Λ diagram, a substrate 30 is first provided, and a silicon nitride layer 31 is used to cover the material 30, and then formed. The first photoresist 32 is on the silicon nitride layer 31, thereby defining the positions of the two and trench isolation regions. They are shown in Figure 3 with sulfur fluoride, carbon fluoride gas, and nitrogen.

449824 ^^ 118023 said amendment 5. Description of invention (8) area. Here, the remaining _32 is equal, and the edge of the silicon nitride layer 31 will not be inclined to the first photoresist by an angle of about 82 degrees. "Remove the 32th photoresist 32" and remove it. The two trench isolation areas are formed by these injured substrates 30. As shown in the third D-mail-upper A departure zone, the movement is different from the above; 丨 the electric material 34 fills these grooves to isolate & and remove the remaining (not located in the shallow shallow groove of the peptide FΑ 麻 Ή) . Here, the thickness of the silicon nitride layer 31 in the & nr eat one / Shi Yousha ^ away zone) in the & left nitride nitride layer will also be slightly reduced. As shown in the third E diagram ' The first conductor layer is called 30 on the substrate, and then a second photoresistor 36 is formed on the conductor layer π ^; the resistor 36 is used to define-the gate position in these grooves "off zone = conductor: 3 second r division: two unfinished It is compounded by the above-mentioned gaseous sulfur (SF6) in * 2 in the example of 2. δ%, and the tertiary carbon (CHF3) is compounded in the ratio of 14% -A, and carbon tetrafluoride (CF4) is formulated with a mixing ratio of 5.7% to ～ $%, and nitrogen (N2) is mixed at a ratio of 5.2% to 2J%, and finally, argon (Ar) is a percentage Of a certain scene of 84.9, θ :. Proportioning is based on this proportion. Obviously, this embodiment can avoid the phenomenon of large-angle excessive tilt of the semiconductor system, so as to maintain the shape of the etching process, such as the Pan-Hidden surface HETHSJBMBWHKmWin I surface- ------ Page II 449824

Page 12

Claims (1)

449824 B _ Cable No. 8811823 VI. Application for patent scope 1. A method for hard nitride removal in semiconductor manufacturing process, which at least includes: a chemical gas etch of the first military layer to provide a substrate, and a nitride layer covering the substrate A photoresist layer is formed on the nitride layer, and the location of the isolation region is defined; at least two trenches are defined by the core, and a mixed etching gas of sulfur fluoride (SFe) 'fluoride gas and nitrogen exhaust gas is removed. The layer of gaseous material that is not covered by the photoresist layer in February. The π1 layer is covered with a portion of the nitride 2. As the method of the scope of application for patent application 丨, a quantitative mixing ratio of 2.8% is formulated. The above-mentioned sulfur fluoride (SF6) is the method according to item 3 in the scope of patent application, wherein the above-mentioned carbonized i gas contains at least carbon trifluoride (CHF3) and carbon tetrafluoride (Cf4). The method of the first item in the scope 'where the above nitrogen is formulated with a quantitative mixing ratio of one percent of 5.2. 5. The method of the first item in the scope of the patent application' wherein the above inert gas contains at least argon (Ar). 6 . —Semi-nitride removal in semiconductor process The chemical gas etching method for a silicon hard mask layer includes at least: providing a substrate 'and covering the substrate with a silicon nitride layer; forming a photoresist layer on the nitride silicon layer to define at least two trenches 449824 _ Case No. 8811823 6. The location of the canal isolation area of the patent application scope; and the use of fluorine and sulphur 'carbon fluoride gas, gas condensate, to remove the mixed money engraved by the photoresist layer ^ even ^' and rat gas Qi7. For example, the patent application Fanyuan No. 6 Fang Ganshi L \ layer of 28% _. .Π method, where the above-mentioned sulfur fluoride (SF6) with the knife &lt; two << one 疋 罝 mixing ratio Match. 8. If the scope of the patent application is the 6th item, the soil, + 6 people-s &amp; mountain negative method, wherein the above fluorinated carbon gas to ν already contains difluoride ((: liver 3) and tetrafluoride) Carbon (cf4). 9. The method according to item 6 of the patent application, wherein the above nitrogen nitrogen is mixed with a quantitative mixing ratio of one of 5.2 percent. 10. The method according to item 6 of the patent application, wherein Argon (Ar) is formulated at a quantitative mixing ratio of one of 8, 4 and 9. 11-A method for forming a shallow trench isolation and gate, including at least: providing a substrate and covering it with a silicon nitride layer The substrate; forming a first photoresist on the silicon nitride layer, thereby defining the position of at least two trench isolation areas; removing the mixed gas with sulfur fluoride, carbon fluoride gas, nitrogen, and inert gas to remove The portion not covered by the first photoresistor is nitrided; a layer is formed to form at least two openings in the trench isolation areas; removing the first photoresistor; removing a portion exposed by the openings This substrate forms the second trench isolation zone, Page 14 449824 Case No. 8811823 Revised Page 15