CN104860259A - Low-pressure vapor-phase etching method - Google Patents
Low-pressure vapor-phase etching method Download PDFInfo
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- CN104860259A CN104860259A CN201410066945.3A CN201410066945A CN104860259A CN 104860259 A CN104860259 A CN 104860259A CN 201410066945 A CN201410066945 A CN 201410066945A CN 104860259 A CN104860259 A CN 104860259A
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Abstract
The invention discloses a low-pressure vapor-phase etching method. The low-pressure vapor-phase etching method comprises the following steps: conveying liquid-state hydrofluoric acid serving as a raw material to a vaporizing device; vaporizing the liquid-state hydrofluoric acid into mixed gas of hydrogen fluoride gas and water vapor; dehydrating the mixed gas to separate hydrogen fluoride gas out; introducing the hydrogen fluoride gas into a process cavity; carrying out a vapor-phase etching reaction in the process cavity by taking the hydrogen fluoride gas as an etching agent, and keeping a low-pressure state in the process cavity in order that water generated by the reaction exists in a gas-state form; and ending the vapor-phase etching reaction. The liquid-state hydrofluoric acid is taken as a reactant raw material, so that the process cost can be reduced, and the safety is enhanced. Moreover, both gas supplied to the process cavity and a product of the etching reaction exist in the process cavity in gas-state forms, so that adhesion is avoided.
Description
Technical field
The present invention relates to microfabrication technology, particularly relate to a kind of gas phase lithographic method.
Background technology
Microelectromechanical systems (MEMS) field is one of popular research field of current scientific and technological circle.Usually, process a MEMS to need to pass through in multistep operations such as Grown structure sheaf, sacrifice layer, mask layers.MEMS is made up of multiple material, and often kind of material plays irreplaceable effect in MEMS, and wherein, silica is commonly used for sacrificial layer material.In order to form unsettled and bascule, in last process prepared by MEMS, need etching, releasing sacrificial layer.
At present, etching silicon dioxide sacrifice layer many employings hydrogen fluoride gas, hydrogen fluoride gas generates the SiF of gaseous state as corrosive gas and silicon dioxde reaction
4and aqueous water, in MEMS sacrificial layer release process, MEMS structure adhesion is caused in order to prevent aqueous water, comparatively common way is mixed ethanol gas in hydrogen fluoride gas, alcohol gas is not only as catalyst but also as drier, and the reaction of catalytic fluorination hydrogen and silica also takes away the aqueous water reacting and generate.But, directly supply hydrogen fluoride and the silicon dioxde reaction of gaseous state, process costs can be caused higher, and security is poor.In addition, the reaction rate of the mist etching silicon dioxide of hydrogen fluoride and ethanol is still comparatively slow, causes the MEMS preparation technology cycle longer, reduces the productive rate of MEMS.
Summary of the invention
The object of this invention is to provide a kind of low-pressure vapor phase lithographic method, process costs, efficiently safer can be reduced.
For achieving the above object, the low-pressure vapor phase lithographic method that the present invention proposes, comprising: using liquid hydrofluolic acid as feedstock transportation to vapourizing unit; Liquid hydrofluolic acid becomes the mist of hydrogen fluoride gas and steam after vaporization; Mist is isolated hydrogen fluoride gas after processed; Hydrogen fluoride gas passes in process cavity; Hydrogen fluoride gas carries out gas phase etching reaction as etching agent in process cavity, and makes to keep low-pressure state to exist in a gaseous form with the water making reaction generate in process cavity; Gas phase etching reaction terminates.
According to an embodiment of low-pressure vapor phase lithographic method of the present invention, be by nitrogen, liquid hydrofluolic acid is blown to vapourizing unit.
According to an embodiment of low-pressure vapor phase lithographic method of the present invention, by vacuum system, process cavity is vacuumized, to make the low-pressure state needed for process cavity maintenance.
According to an embodiment of low-pressure vapor phase lithographic method of the present invention, control by automatic pressure controller the degree that vacuum system vacuumizes.
According to an embodiment of low-pressure vapor phase lithographic method of the present invention, the air pressure in vacuum system Controlling Technology chamber is lower than 50torr.
According to an embodiment of low-pressure vapor phase lithographic method of the present invention, to the processed of mist by carrying out condensation process to mist, moisture condensation wherein being separated out and becomes liquid, isolating hydrogen fluoride gas.
According to an embodiment of low-pressure vapor phase lithographic method of the present invention, after terminating with gas phase etching technics before process cavity supply hydrogen fluoride gas, again process cavity is vacuumized by being filled with nitrogen to process cavity, so repeatedly for several times with process for purifying chamber.
According to an embodiment of low-pressure vapor phase lithographic method of the present invention, before hydrogen fluoride gas is passed in process cavity, in process cavity, first input the hydrofluoric acid of the gaseous state without processed, after gas phase etching reaction in process cavity carries out a time period, stop the hydrofluoric acid of the gaseous state inputted in process cavity without processed.
According to an embodiment of low-pressure vapor phase lithographic method of the present invention, while hydrogen fluoride gas is passed in process cavity, in process cavity, input catalytic gas, after the gas phase etching reaction in process cavity carries out a time period, stop in process cavity, input catalytic gas.
According to an embodiment of low-pressure vapor phase lithographic method of the present invention, catalytic gas is water vapour or alcohol gas.
Compared with prior art, the low-pressure vapor phase lithographic method that the present invention proposes has the following advantages:
1, owing to being directly adopt hydrogen fluoride gas as reactant feed in conventional method, and hydrogen fluoride gas belongs to hypertoxic gas.The present invention using the hydrofluoric acid of liquid state as reactant feed, and the mist of hydrogen fluoride gas and steam is converted into by physical method, for etching reaction, with directly adopt hydrogen fluoride gas (HF gas) as reactant feed conventional method compared with, required cost is lower, and safer.
2, the air pressure in process cavity is remained on lower setting value by vacuum system by the present invention, in this setting value, is supplied to gas in process cavity and reaction product water is present in process cavity all in a gaseous form, can not sticks together.
3, the present invention passes into the mist of hydrogen fluoride gas and water vapour in the starting stage that gas phase etches to process cavity, and water vapour, as catalyst, can impel the fast reaction of hydrogen fluoride and silica, improves reaction rate.
4, gas phase etching reaction of the present invention carries out in the gaseous state, and reactant carries out chemical reaction with molecular state, therefore, can etch finer structure, such as NEMS or the making of nano level IC circuit etc.
5, the present invention etches the SiO of isodose
2it is low that required hydrofluoric acid price compares required HF.
Accompanying drawing explanation
Fig. 1 shows the flow chart of the preferred embodiment of low-pressure vapor phase lithographic method of the present invention.
Fig. 2 shows the schematic diagram of low-pressure vapor phase lithographic method of the present invention.
Detailed description of the invention
By describing technology contents of the present invention, structural feature in detail, reached object and effect, coordinate graphic being described in detail below in conjunction with embodiment.
Fig. 1 shows the flow process of the preferred embodiment of low-pressure vapor phase lithographic method of the present invention.Fig. 2 shows the principle of low-pressure vapor phase lithographic method.Please simultaneously see Fig. 1 and Fig. 2, here is the detailed description of each implementation step of low-pressure vapor phase lithographic method to the present embodiment.
Step S1: using liquid hydrofluolic acid as feedstock transportation to vapourizing unit.
Refer to Fig. 2, liquid hydrofluolic acid (such as concentration is the hydrofluoric acid of 50%) can be stored in hydrofluoric acid holding vessel, and the input of vapourizing unit is connected with hydrofluoric acid holding vessel by pipeline.By nitrogen, liquid hydrofluolic acid is blown to vapourizing unit.
Step S2: liquid hydrofluolic acid becomes the mist of hydrogen fluoride gas and steam after vaporization.
Refer to Fig. 2, vapourizing unit vaporization hydrofluoric acid, makes liquid hydrofluoric acid be transformed into the hydrofluoric acid (mist of hydrogen fluoride gas and steam) of gaseous state.
Step S3: mist is isolated hydrogen fluoride gas after processed.
Refer to Fig. 2, the input of dewater unit connects the output of vapourizing unit by pipeline, the mist of hydrogen fluoride gas and steam enters into dewater unit.
Preferably a kind of processed is condensation process, such as dewater unit is cooler, mist enters in cooler, typical condensing condition is pressure 101325Pa, temperature is 30 DEG C, higher and the hydrofluoric boiling point of boiling point due to water is lower, and therefore water condensation is separated out and become liquid, and hydrogen fluoride gas is then separated.It will be understood by those skilled in the art that, the quantity of cooler is not limited in one, in order to reduce gaseous state hydrofluoric acid in the content of steam, two or more cooler can be set, make the hydrofluoric acid of gaseous state successively by each cooler, with the content of steam in the hydrofluoric acid reducing gaseous state.
Step S4: hydrogen fluoride gas passes in process cavity.
The input of process cavity connects the output of dewater unit by pipeline, the hydrogen fluoride gas after processed is transported in process cavity.
Step S5: hydrogen fluoride gas carries out gas phase etching reaction as etching agent in process cavity, and make in process cavity, to keep low-pressure state to exist in a gaseous form with the water making reaction generate.
As shown in Figure 2, vacuum system Joining Technology chamber, before process cavity input hydrogen fluoride gas, vacuum system vacuumizes process cavity, by the air pressure in an automatic pressure controller (not shown) Controlling Technology chamber, the air pressure in process cavity is made to remain on lower setting value (generally lower than 50torr), in this setting value, the product water of the gas and hydrogen fluoride gas and silicon dioxde reaction that are supplied to process cavity is present in process cavity all in the form of a vapor, avoids sticking together.
In one embodiment, in the starting stage of gas phase etching, namely before hydrogen fluoride gas is passed in process cavity, in process cavity, first input the hydrofluoric acid (mist of hydrogen fluoride gas and water vapour) of the gaseous state without processed, the water (being present in the form of a vapor in process cavity) that a certain amount of water vapour contained in the hydrofluoric acid of gaseous state and hydrogen fluoride gas and silicon dioxde reaction generate, as the catalyst of hydrogen fluoride gas and silicon dioxde reaction, can promote hydrogen fluoride gas (HF gas) and silica fast reaction.The chemical reaction (etching reaction) occurred in process cavity 104 is as follows:
4HF+SiO
2==SiF
4(gas)+2H
2o (gas)
After gas phase etching reaction in process cavity carries out a time period, stop the hydrofluoric acid of the gaseous state inputted in process cavity without processed, then hydrogen fluoride gas isolated from the hydrofluoric acid of gaseous state is passed in process cavity to carry out gas phase etching reaction.
In one embodiment, while passing in process cavity by hydrogen fluoride gas, in process cavity, input catalytic gas, after the gas phase etching reaction in process cavity carries out a time period, stop in process cavity, input catalytic gas.This catalytic gas is water vapour or alcohol gas.Its object is to, in the starting stage of gas phase etching, in process cavity, input catalytic gas can promote hydrogen fluoride gas (HF gas) and silica fast reaction.
Step S6: gas phase etching reaction terminates.
After terminating with gas phase etching technics before process cavity supply hydrogen fluoride gas, preferably, can vacuumize process cavity again by being filled with nitrogen to process cavity, so repeatedly for several times with process for purifying chamber.
Compared with prior art, the low-pressure vapor phase lithographic method that the present invention proposes has the following advantages:
1. the present invention using the hydrofluoric acid of the liquid state of high concentration as reactant feed, and vaporized by physical method, condensation, isolate hydrogen fluoride gas for etching silicon dioxide, and directly adopt hydrogen fluoride gas as compared with reactant feed, required cost is lower, and safer.
2. the present invention is by the air pressure in automatic pressure controller Controlling Technology chamber, the air pressure in process cavity is made to remain on lower setting value, in this setting value, be supplied to gas in process cavity and reaction product water is present in process cavity all in the form of a vapor, avoid sticking together.
3. the present invention passes into the mist of hydrogen fluoride gas and water vapour in the starting stage that gas phase etches to process cavity, and water vapour, as catalyst, can impel the fast reaction of hydrogen fluoride gas and silica, improves reaction rate.
4. gas phase etching reaction of the present invention carries out in the gaseous state, and reactant carries out chemical reaction with molecular state, therefore, can etch finer structure, such as NEMS or the making of nano level IC circuit etc.
In sum, the present invention is illustrated by above-mentioned embodiment and correlative type, and what oneself was concrete, full and accurate discloses correlation technique, and those skilled in the art can be implemented according to this.And the above embodiment be only used to illustrate the present invention, instead of be used for restriction of the present invention, interest field of the present invention, should be defined by claim of the present invention.Still all interest field of the present invention should be belonged to as the change of described component number herein or the replacement etc. of equivalence element.
Claims (10)
1. a low-pressure vapor phase lithographic method, comprising:
Using liquid hydrofluolic acid as feedstock transportation to vapourizing unit;
Liquid hydrofluolic acid becomes the mist of hydrogen fluoride gas and steam after vaporization;
Mist is isolated hydrogen fluoride gas after processed;
Hydrogen fluoride gas passes in process cavity;
Hydrogen fluoride gas carries out gas phase etching reaction as etching agent in process cavity, and makes to keep low-pressure state to exist in a gaseous form with the water making reaction generate in process cavity;
Gas phase etching reaction terminates.
2. low-pressure vapor phase lithographic method according to claim 1, is characterized in that, is blown liquid hydrofluolic acid to vapourizing unit by nitrogen.
3. low-pressure vapor phase lithographic method according to claim 1, be is characterized in that, vacuumized by vacuum system to process cavity, to make the low-pressure state needed for process cavity maintenance.
4. low-pressure vapor phase lithographic method according to claim 3, is characterized in that, controls by automatic pressure controller the degree that vacuum system vacuumizes.
5. low-pressure vapor phase lithographic method according to claim 3, is characterized in that, the air pressure in vacuum system Controlling Technology chamber is lower than 50torr.
6. low-pressure vapor phase lithographic method according to claim 1, is characterized in that, to the processed of mist by carrying out condensation process to mist, moisture condensation wherein being separated out and becomes liquid, isolating hydrogen fluoride gas.
7. low-pressure vapor phase lithographic method according to claim 1, it is characterized in that, after terminating with gas phase etching technics before process cavity supply hydrogen fluoride gas, again process cavity is vacuumized by being filled with nitrogen to process cavity, so repeatedly for several times with process for purifying chamber.
8. low-pressure vapor phase lithographic method according to claim 1, it is characterized in that, before hydrogen fluoride gas is passed in process cavity, in process cavity, first input the hydrofluoric acid of the gaseous state without processed, after gas phase etching reaction in process cavity carries out a time period, stop the hydrofluoric acid of the gaseous state inputted in process cavity without processed.
9. low-pressure vapor phase lithographic method according to claim 1, it is characterized in that, while passing in process cavity by hydrogen fluoride gas, in process cavity, input catalytic gas, after gas phase etching reaction in process cavity carries out a time period, stop in process cavity, input catalytic gas.
10. low-pressure vapor phase lithographic method according to claim 9, is characterized in that, described catalytic gas is water vapour or alcohol gas.
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| CN201410066945.3A CN104860259A (en) | 2014-02-26 | 2014-02-26 | Low-pressure vapor-phase etching method |
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Citations (6)
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| WO2000046838A2 (en) * | 1999-02-05 | 2000-08-10 | Massachusetts Institute Of Technology | Hf vapor phase wafer cleaning and oxide etching |
| KR100381011B1 (en) * | 2000-11-13 | 2003-04-26 | 한국전자통신연구원 | Stiction-free release method of microstructure for fabrication of MEMS device |
| JP2004247539A (en) * | 2003-02-14 | 2004-09-02 | Sumitomo Mitsubishi Silicon Corp | Method for evaluating hf defect of soi wafer |
| US20060177987A1 (en) * | 1997-05-09 | 2006-08-10 | Bergman Eric J | Methods for forming thin oxide layers on semiconductor wafers |
| CN101500935A (en) * | 2006-08-02 | 2009-08-05 | 点35微结构有限公司 | Method of etching a sacrificial silicon oxide layer |
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2014
- 2014-02-26 CN CN201410066945.3A patent/CN104860259A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN86105419A (en) * | 1985-08-28 | 1987-04-29 | Fsi公司 | Gaseous process and equipment from the substrate removing films |
| US20060177987A1 (en) * | 1997-05-09 | 2006-08-10 | Bergman Eric J | Methods for forming thin oxide layers on semiconductor wafers |
| WO2000046838A2 (en) * | 1999-02-05 | 2000-08-10 | Massachusetts Institute Of Technology | Hf vapor phase wafer cleaning and oxide etching |
| KR100381011B1 (en) * | 2000-11-13 | 2003-04-26 | 한국전자통신연구원 | Stiction-free release method of microstructure for fabrication of MEMS device |
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Application publication date: 20150826 |