CN117736739A - High-selectivity etching solution for semiconductor silicon oxide layers with different ion doping concentrations, and preparation method and application thereof - Google Patents
High-selectivity etching solution for semiconductor silicon oxide layers with different ion doping concentrations, and preparation method and application thereof Download PDFInfo
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- 125000003158 alcohol group Chemical group 0.000 claims description 2
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- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Inorganic materials [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 abstract description 8
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Abstract
The invention relates to high-selectivity etching of a semiconductor silicon oxide layer with different ion doping concentrations, which comprises the following components in parts by weight: 1-10 parts of 49wt% hydrofluoric acid solution; 2-20 parts of 40wt% ammonium fluoride solution; 50-90 parts of a solvent; 1-10 parts of masking agent; 0.1-5 parts of thickener. The invention also discloses a preparation method and application of the etching solution. The etching solution can selectively etch the P-type oxide to obtain an oxide layer with similar film thickness. The masking agent is a positively charged electrophile, can selectively combine with free electrons of the N-type oxide, benzene molecules form steric hindrance around the N-type oxide, the surface of the masking agent is covered by F atoms to form a hydrophobic oleophobic layer, and hydrofluoric acid is prevented from combining with Si-O bonds on the surface of the N-type oxide, so that the etching of the N-type oxide is inhibited, and the P-type oxide is selectively etched.
Description
Technical Field
The invention belongs to the field of semiconductor manufacturing processes, and particularly relates to a high-selectivity etching solution for semiconductor silicon oxide layers with different ion doping concentrations, a preparation method and application thereof.
Background
The ion doping technology is widely applied in the field of semiconductors, and can realize the performance optimization of semiconductor devices. The ion beam is injected into the material to interact with material atoms, so that the physical and chemical properties of the material are changed, the conductivity, optical properties, magnetism, mechanical properties and the like of the material are changed, and the accurate regulation and control of the material properties are realized.
In the process of semiconductor wafer, it is often necessary to obtain different types of silicon oxide film by adjusting the type and concentration of doped ions, to dope trace amounts of group VA impurity atoms (such as phosphorus, arsenic, antimony, etc.) into silicon oxide to obtain N-type oxide (phosphosilicate glass), and to dope trace amounts of group IIIA impurity atoms (such as boron, indium, etc.) to obtain P-type oxide (borosilicate glass).
Under the advanced background of chip manufacturing Cheng Yufa, the number of thin film deposition processes and layers are increased, so that the number of metal layers is driven to be increased, and the borophosphosilicate glass is widely applied as the most common pre-metal dielectric and inter-metal dielectric.
For N-type and P-type oxides, the doping effects of the higher and lower cations are different from those of Si, so that the structure and properties of the network change when the silicon atoms are replaced.
At a certain etching temperature, the etching rate depends on the proportion of the etching solution and the doping condition of silicon dioxide. The higher the phosphorus doping concentration is, the more loose the network structure is, and the faster the corrosion is; the higher the boron doping concentration, the greater the grid strength and the slower the corrosion. Under the same etching conditions, the N-type oxide etching rate is far greater than the P-type oxide etching rate. After DHF treatment, a height difference is formed, which is unfavorable for the subsequent process, and therefore, an etching solution for selectively etching P-type oxide needs to be developed to obtain an oxide layer with similar film thickness.
Disclosure of Invention
The invention solves the technical problems that: an etching solution for selectively etching a P-type oxide is provided to obtain an oxide layer having a similar film thickness.
In view of the technical problems in the prior art, the invention designs a high-selectivity etching solution for semiconductor silicon oxide layers with different ion doping concentrations, and a preparation method and application thereof.
In order to solve the technical problems, the invention adopts the following scheme:
the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations is characterized by comprising the following components in parts by weight:
wherein the masking agent is borane with strong Lewis acidity;
the solvent is a mixed solution of deionized water and an organic solvent, and the organic solvent is an alcohol ether solvent.
Further, the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations is characterized by comprising the following components in parts by weight:
further, the thickener is one or more of carboxymethyl cellulose, methyl cellulose, sodium starch phosphate, sodium carboxymethyl cellulose, sodium polyacrylate and polyoxyethylene.
Further, the alcohol ether solvent is one or more of ethylene glycol methyl ether, ethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol butyl ether and diethylene glycol monohexyl ether;
further, the alcohol ether solvent is ethylene glycol butyl ether;
the masking agent is one or two of tri (pentafluorophenyl) borane and di (pentafluorophenyl) borane;
the thickener is carboxymethyl cellulose.
Further, the mass ratio of the deionized water to the organic solvent is 1:1-10:1.
Further, the mass ratio of the deionized water to the organic solvent is 5:1-10:1.
The invention also discloses a preparation method of the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations, which is characterized by comprising the following steps:
step 1: weighing the components respectively;
step 2: mixing deionized water and an organic solvent according to a mass ratio, adding a thickening agent, and stirring for 10-30min to obtain a solution A;
step 3: adding the weighed masking agent into the solution A obtained in the step 2, and stirring for 5-10min to obtain a solution B;
step 4: and (3) sequentially adding 40wt% ammonium fluoride solution and 49wt% hydrofluoric acid solution into the solution B obtained in the step (3), mixing and stirring for 10-20min, and obtaining the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations.
The invention also discloses an etching method of the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations, which is characterized by comprising the following steps:
step 1: placing the high-selectivity etching solution prepared by the method for the semiconductor silicon oxide layers with different ion doping concentrations in a 40L chemical tank, keeping the temperature between 20 ℃ and 25 ℃, circulating the etching solution at the speed of 4-5L/min for 5-10min, and vertically placing the wafer in the clamping tank;
step 2: after etching is finished, placing the wafer in a chemical tank filled with ultrapure water, circulating the ultrapure water in the tank at a speed of 4-5L/min, and taking out after placing for 5-10min in a circulating way;
step 3: and (5) blowing the surface of the wafer with high-purity nitrogen with the flow of 100L/min for 1-3min, thus finishing the etching treatment of the silicon oxide layer on the surface of the wafer.
The invention also discloses application of the high-selectivity etching solution to etching of the silicon oxide wafer of the semiconductor silicon oxide layers with different ion doping concentrations.
In the invention, the alcohol ether solvent is polyhydroxy solvent, has good dissolution assisting effect, and is also an electrophile, which can be selectively distributed near the N-type oxide layer to a certain extent, promote the masking agent to react with the N-type oxide and inhibit the etching of the N-type oxide.
In the invention, the thickening agent carboxymethyl cellulose has high thickening efficiency, enhances rheological property, controls the flow speed of liquid, and can be effectively matched with a masking agent to be adsorbed on the N-type surface.
In the invention, the total viscosity of the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations, which is prepared by the preparation method, is 50-80 mPa.s, and the high-selectivity etching solution has a good effect.
The high selectivity mechanism in the invention is as follows:
the masking agent tris (pentafluorophenyl) borane and/or bis (pentafluorophenyl) borane is a positively charged electrophile, can selectively combine with free electrons of the N-type oxide, benzene molecules surround to form steric hindrance, the surface of the benzene molecules is covered by fluorine atoms to form a hydrophobic and oleophobic layer, and hydrofluoric acid is prevented from combining with surface Si-O bonds, so that etching of the N-type oxide is inhibited, and the P-type oxide is selectively etched.
It should be noted that, in the present invention, unless otherwise specified, reference to the specific meaning of "comprising" as defined and described by the composition includes both the open meaning of "comprising", "including" and the like, and the closed meaning of "consisting of …" and the like.
The invention provides a high-selectivity etching solution for semiconductor silicon oxide layers with different ion doping concentrations, and a preparation method and application thereof have the following beneficial effects:
(1) The high-selectivity etching liquid for the semiconductor silicon oxide layers with different ion doping concentrations can selectively etch the P-type oxide to obtain the oxide layers with similar film thickness.
(2) The masking agent realizes high selectivity of the etching solution, is a positively charged electrophile, can selectively combine with free electrons of the N-type oxide, forms steric hindrance around benzene molecules, and covers the surface by F atoms to form a hydrophobic and oleophobic layer, so that hydrofluoric acid is prevented from combining with Si-O bonds on the surface, and etching of the N-type oxide is inhibited, and the P-type oxide is selectively etched.
(3) The organic solvent is introduced to better dissolve the masking agent, the alcohol ether solvent is a polyhydroxy solvent and is also an electrophile, and the alcohol ether solvent can be selectively distributed near the N-type oxide layer to a certain extent, promote the masking agent to react with the N-type oxide and inhibit the etching of the N-type oxide.
(4) The thickener can increase the steric hindrance of the etching solution, so that the mass transfer rate of the etching solution is reduced, and a better etching effect is achieved within a certain viscosity range.
Drawings
Fig. 1: an SEM image of the surface morphology after 60000 x magnification was obtained by etching with the etching solution of example 1;
fig. 2: an SEM image of the surface morphology at 2000 x magnification after etching with the etching solution of comparative example 1;
fig. 3: the SEM image of the surface morphology after etching with the etching solution of comparative example 3 was magnified 100000 times.
Detailed Description
The invention is further described with reference to specific examples and figures:
table 1: example 1-example 10
Table 2: comparative example 1-comparative example 3
Table 3: test results
Regarding the preparation method of the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations, disclosed by the invention, the preparation method comprises the following steps:
comprises the following steps:
the preparation method of examples 1-4 is as follows:
step 1: weighing the components respectively;
step 2: mixing deionized water and an organic solvent according to a mass ratio, adding a thickening agent, and stirring for 20min to obtain a solution A;
step 3: adding the weighed masking agent into the solution A obtained in the step 2, and stirring for 8min to obtain a solution B;
step 4: and (3) sequentially adding 40wt% ammonium fluoride solution and 49wt% hydrofluoric acid solution into the solution B obtained in the step (3), mixing and stirring for 15min, and obtaining the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations.
The preparation method of examples 5-7 is as follows:
step 1: weighing the components respectively;
step 2: mixing deionized water and an organic solvent according to a mass ratio, adding a thickening agent, and stirring for 10min to obtain a solution A;
step 3: adding the weighed masking agent into the solution A obtained in the step 2, and stirring for 10min to obtain a solution B;
step 4: and (3) sequentially adding 40wt% ammonium fluoride solution and 49wt% hydrofluoric acid solution into the solution B obtained in the step (3), mixing and stirring for 20min, and obtaining the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations.
The preparation method of examples 8-10 is as follows:
step 1: weighing the components respectively;
step 2: mixing deionized water and an organic solvent according to a mass ratio, adding a thickening agent, and stirring for 30min to obtain a solution A;
step 3: adding the weighed masking agent into the solution A obtained in the step 2, and stirring for 5min to obtain a solution B;
step 4: and (3) sequentially adding 40wt% ammonium fluoride solution and 49wt% hydrofluoric acid solution into the solution B obtained in the step (3), mixing and stirring for 10min, and obtaining the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations.
Regarding the etching method of the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations, the invention comprises the following steps:
the method comprises the following steps:
step 1: placing the high-selectivity etching solution prepared by the method for the semiconductor silicon oxide layers with different ion doping concentrations in a 40L chemical tank, keeping the temperature between 22 ℃, circulating the etching solution at the speed of 4L/min for 5min, and vertically placing the wafer in the clamping tank;
step 2: after etching is finished, placing the wafer in a chemical tank filled with ultrapure water, circulating the ultrapure water in the tank at a speed of 5L/min, and taking out after placing for 8 min;
step 3: and (5) blowing the surface of the wafer with high-purity nitrogen with the flow of 100L/min for 2min, thus finishing the etching treatment of the silicon oxide layer on the surface of the wafer.
Regarding performance testing and description:
in order to examine the influence of the surface selective agent on the selective etching of the silicon oxide film layers with different doping concentrations, the following technical means are adopted: etching solutions are respectively prepared according to the proportion, etching experiments are carried out, then the thickness of the silicon oxide film layers with different doping concentrations is measured by using a film thickness meter, and the selective etching ratio is calculated.
Performance test 1
The etching rate measuring method comprises the following steps:
SiO was measured by a film thickness meter 2 Film thickness, etching rate= (film thickness before etching-film thickness after etching)) /etching time.
Performance test 2
The viscosity measurement method comprises the following steps:
the solution viscosity is preferably 50 to 80 mPas as measured by a viscometer.
Analysis of test results shows that:
as can be seen from Table 3, in the first place, the viscosities of the highly selective etching solutions prepared in the examples of the present invention are all in the range of 50 to 80 mPas, which is an optimum viscosity, and the viscosity base of the highly selective etching solution is excellent.
Second, the high selectivity etching solution P-type SiO prepared by the embodiment of the invention 2 The etching rate is above 60nm/min, and for N-type SiO 2 The etching rate is below 15nm/min, the etching selectivity (P type/N type) is above 9, and the data show that the high-selectivity etching solution prepared by the embodiment of the invention has high selectivity for etching the P type oxide.
As can also be seen from the above data of the comparative example, the etching solution prepared in the comparative example has poor selectivity for etching P-type oxide.
Further contrasted by the attached drawings in the specification:
FIG. 1 is an SEM image of the surface morphology of 60000 times magnification after etching with the etching solution of example 1; as can be seen from fig. 1, the left side is P-type oxide, the right side is N-type oxide, and a height difference of about 300nm is formed after etching, which proves that the etching solution in embodiment 1 can selectively etch P-type oxide.
FIG. 2 is an SEM image of the surface morphology at 2000 Xmagnification after etching with the etching solution of comparative example 1; as can be seen from fig. 2, the left side is P-type oxide, the right side is N-type oxide, and a height difference of about 100nm is formed after etching, which proves that the etching solution of comparative example 1 has a faster etching rate for N-type oxide.
FIG. 3 is an SEM image of the surface morphology of 100000 times enlarged after etching with the etching solution of comparative example 3; as can be seen from fig. 3, the left side is P-type oxide, the right side is N-type oxide, and there is no level difference after etching, which proves that comparative example 3 has no selective etching property for P-type oxide.
Compared with the prior art, the invention has the following advantages:
the high-selectivity etching liquid for the semiconductor silicon oxide layers with different ion doping concentrations can selectively etch the P-type oxide to obtain the oxide layers with similar film thickness. The masking agent is a positively charged electrophile, can selectively combine with free electrons of the N-type oxide, benzene molecules form steric hindrance around the free electrons, the surface of the benzene molecules is covered by F atoms to form a hydrophobic oleophobic layer, and the hydrofluoric acid is prevented from combining with Si-O bonds on the surface, so that the etching of the N-type oxide is inhibited, and the P-type oxide is selectively etched. The organic solvent is introduced to better dissolve the masking agent, the alcohol ether solvent is a polyhydroxy solvent and is also an electrophile, and the alcohol ether solvent can be selectively distributed near the N-type oxide layer to a certain extent, promote the masking agent to react with the N-type oxide and inhibit the etching of the N-type oxide. The thickener is introduced to increase the steric hindrance of the solution, so that the mass transfer rate of the solution is reduced, and a better etching effect is achieved within a certain viscosity range.
While the present invention has been described above by way of example with reference to the embodiments and the accompanying drawings, it is apparent that the implementation of the present invention is not limited by the above manner, and it is within the scope of the present invention to apply the inventive concept and technical solution to other situations as long as various improvements are adopted by the inventive concept and technical solution, or without any improvement.
Claims (10)
1. The high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations is characterized by comprising the following components in parts by weight:
wherein the masking agent is borane with strong Lewis acidity;
the solvent is a mixed solution of deionized water and an organic solvent, and the organic solvent is an alcohol ether solvent.
2. The high selectivity etching solution for semiconductor silicon oxide layers with different ion doping concentrations according to claim 1, which is characterized by comprising the following components in parts by weight:
3. the high selectivity etching solution for semiconductor silicon oxide layers of different ion doping concentrations according to claim 2, wherein:
the thickener is one or more of carboxymethyl cellulose, methyl cellulose, sodium starch phosphate, sodium carboxymethyl cellulose, sodium polyacrylate and polyoxyethylene.
4. The high selectivity etching solution for semiconductor silicon oxide layers of different ion doping concentrations according to claim 3, wherein:
the alcohol ether solvent is one or more of ethylene glycol methyl ether, ethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol butyl ether and diethylene glycol monohexyl ether.
5. The high selectivity etching solution for semiconductor silicon oxide layers with different ion doping concentrations according to claim 4, wherein:
the alcohol ether solvent is ethylene glycol butyl ether;
the masking agent is one or two of tri (pentafluorophenyl) borane and di (pentafluorophenyl) borane;
the thickener is carboxymethyl cellulose.
6. The high selectivity etching solution for semiconductor silicon oxide layers with different ion doping concentrations according to claim 5, wherein:
the mass ratio of the deionized water to the organic solvent is 1:1-10:1.
7. The high selectivity etching solution for semiconductor silicon oxide layers with different ion doping concentrations according to claim 6, wherein:
the mass ratio of the deionized water to the organic solvent is 5:1-10:1.
8. A method for preparing the high selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations according to any one of claims 1 to 7, comprising the following steps:
step 1: weighing the components respectively;
step 2: mixing deionized water and an organic solvent according to a mass ratio, adding a thickening agent, and stirring for 10-30min to obtain a solution A;
step 3: adding the weighed masking agent into the solution A obtained in the step 2, and stirring for 5-10min to obtain a solution B;
step 4: and (3) sequentially adding 40wt% ammonium fluoride solution and 49wt% hydrofluoric acid solution into the solution B obtained in the step (3), mixing and stirring for 10-20min, and obtaining the high-selectivity etching solution for the semiconductor silicon oxide layers with different ion doping concentrations.
9. A method of etching a semiconductor silicon oxide layer of different ion doping concentration using a high selectivity etching solution according to any one of claims 1 to 7, comprising the steps of:
step 1: placing the high-selectivity etching solution prepared by the method for the semiconductor silicon oxide layers with different ion doping concentrations in a 40L chemical tank, keeping the temperature between 20 ℃ and 25 ℃, circulating the etching solution at the speed of 4-5L/min for 5-10min, and vertically placing the wafer in the clamping tank;
step 2: after etching is finished, placing the wafer in a chemical tank filled with ultrapure water, circulating the ultrapure water in the tank at a speed of 4-5L/min, and taking out after placing for 5-10min in a circulating way;
step 3: and (5) blowing the surface of the wafer with high-purity nitrogen with the flow of 100L/min for 1-3min, thus finishing the etching treatment of the silicon oxide layer on the surface of the wafer.
10. Use of a highly selective etching solution according to any one of claims 1 to 7 for etching silicon oxide wafers for semiconductor silicon oxide layers of different ion doping concentrations.
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