CN103021817A - Method of cleaning after wet etching - Google Patents
Method of cleaning after wet etching Download PDFInfo
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- CN103021817A CN103021817A CN2012105797726A CN201210579772A CN103021817A CN 103021817 A CN103021817 A CN 103021817A CN 2012105797726 A CN2012105797726 A CN 2012105797726A CN 201210579772 A CN201210579772 A CN 201210579772A CN 103021817 A CN103021817 A CN 103021817A
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Abstract
The invention discloses a method of cleaning after wet etching to guarantee the surface of a wet-etched silicon wafer to meet the requirement for quality inspection. The method includes: performing first wet removal of silicon dust residue after aluminum wet etching process; forming photoresist on the wet-etched aluminum by photoetching process; drying the photoresist; subjecting the photoresist to dry ashing; and performing second wet removal of silicone dust residue.
Description
Technical field
The invention belongs to semiconductor integrated circuit manufacturing process field, relate to the cleaning method behind a kind of metallic aluminium wet etching.
Background technology
Along with the continuous growth of integrated circuit integrated level, device feature size constantly dwindles in the integrated circuit, and the fine degree of integrated circuit production and processing is also continuing to increase.And manufacture important all the more that the etching technics that determines the device final size in the link just highlights at integrated circuit.At integrated circuit constantly under the requirement of small size development, dry etch process because have good sidewall control ability, good characteristic size control ability, minimum photoresist comes off and sticking problem, good uniformity and good process stabilizing and controllability are widely used.And wet-etching technology is because be isotropic chemical corrosion, all produces corrosion to horizontal and vertical in the etching process, and the characteristic size control ability is poor.In the very lagre scale integrated circuit (VLSIC) of high integration, small-feature-size, re-use hardly.
But the metal wet-etching technology has but that cost is low, production capacity is large, without charge accumulated, without advantages such as physics damages.This so that wet processing in some specialities manufacturing fields, be used widely.Such as power device product, high reliability product, the anti-irradiation products of Aero-Space, MEMS (Micro-electro Mechanical Systems, microelectromechanical systems) etc.
Now widely used metallic aluminium wet-etching technology generally is with aluminium corrosive liquid etching metal, yet because the isotropism of wet etching, corrosive liquid also corrodes the thin oxide layer of aluminium lower floor in the etching metallic aluminium.When the thin oxide layer thickness h less than the distance s between the aluminum strip, then when metallic aluminium when fully etching is clean, thin oxide layer has been corroded totally, backing material silicon also is corroded, and forms silicon and considers to be worth doing and separate out, as shown in Figure 1.Therefore, need to the silicon bits that produce behind the metallic aluminium wet etching be cleaned.Usually adopt the silicon bits that produce behind dry method or the wet processing etching.Please refer to Fig. 2, it is depicted as in the prior art metallic aluminium wet etching and removes silicon bits processing step, comprises the metallic aluminium photoetching, the photoresist oven dry, and photoresist ashing, the wet etching metallic aluminium goes photoresist and dry method or wet method to remove the silicon bits.Wherein, the removing residues after dry method goes method that silicon bits adopt Ions Bombardment with etching, process costs is low, the process time is short, simple to operate, flux is large, is suitable for typical products in mass production production.But use dry process can introduce plasma damage and charge accumulated, reduce reliability and the radioresistance level of product.Wet method goes silicon bits then to adopt residue after the method for chemical corrosion is removed etching, substrate is not produced damage and charge accumulated, avoids plasma damage and charge accumulated on the impact of product reliability and anti-irradiation level.But wet processing goes the ability of silicon bits to compare dry process want a little less than, can't remove the silicon bits fully, can produce the residual problem of silicon bits.In subsequent technique, residual silicon bits can fly away the various piece of silicon chip, form macroscopic stain, thereby can't satisfy On-line Product check and OQC requirement.If the silicon bits are stayed on metal connecting line or the encapsulation welding tray, then can cause integrity problem and encapsulation problem.
Summary of the invention
Main purpose of the present invention is to provide the cleaning method behind a kind of wet etching, satisfies the quality inspection requirement with silicon chip surface after guaranteeing wet etching.For reaching above-mentioned purpose, the cleaning method behind the wet etching of the present invention may further comprise the steps:
After finishing the metallic aluminium wet-etching technology, carry out wet method removal first time silicon and consider to be worth doing residual;
Form photoresist by photoetching process at the metallic aluminium behind wet etching;
Carry out the photoresist oven dry;
Carry out the photoresist dry ashing;
It is residual to carry out wet method removal second time silicon bits.
Preferably, described metallic aluminium wet-etching technology comprises: form patterned photoresist by photoetching process at described metallic aluminium; Carry out the photoresist oven dry; Carry out the photoresist dry ashing; Take photoresist as mask, the described metallic aluminium of wet etching is to form groove, and described groove runs through the thin oxide layer of described metallic aluminium below and extends to substrate, and it is residual to make described substrate produce described silicon bits; Remove described photoresist.
Preferably, the thickness of described thin oxide layer is less than the width of described groove.
Preferably, described photoetching process comprises the coating photoresist layer, exposure and development, and the thickness of wherein said photoresist layer is 2 to 2.5 microns.
Preferably, the temperature of carrying out the photoresist oven dry is 100 to 120 ℃, and the time is 10 to 30 minutes.
Preferably, the podzolic gas that carries out the photoresist dry ashing is carbon tetrafluoride and oxygen, and the ashing time is 10 to 30 seconds.
Preferably, by the described metallic aluminium of aluminium corrosive liquid wet etching, wherein said aluminium corrosive liquid composition comprises 80% phosphoric acid, 5% nitric acid, 5% acetic acid and 10% water; Technological temperature is 35 to 45 ℃.
Preferably, the process gas of removing described photoresist is oxygen, and the time is 30 to 90 minutes.
Preferably, residual by going silicon bits liquid wet method to remove the silicon bits, the wherein said composition of silicon bits liquid that goes comprises 60% ~ 70% phosphoric acid, 5% ~ 10% nitric acid, 10% ~ 20% acetic acid and 10% ~ 20% water; Technological temperature is 23 to 25 ℃, and the time is 1 to 10 minute.
The invention has the advantages that; by having increased the steps such as secondary photoetching metallic aluminium; the protection metallic aluminium is unaffected when increasing wet method to remove the silicon bits residual process time; it is residual and remove residual white residue effectively to reduce silicon bits; can not produce charge accumulated and plasma damage yet; can guarantee reliability and the anti-radiation performance of device and products, satisfy specialities to the requirement of high reliability and highly anti-radiation performance.
Description of drawings
Figure 1 shows that schematic diagram behind the metallic aluminium wet etching with thin oxide layer structure.
Fig. 2 is metallic aluminium wet etching and remove the flow chart of silicon bits technique in the prior art.
Fig. 3 is the flow chart of the cleaning method behind one embodiment of the invention wet etching.
Embodiment
For making content of the present invention more clear understandable, below in conjunction with Figure of description, content of the present invention is described further.Certainly the present invention is not limited to this specific embodiment, and the known general replacement of those skilled in the art also is encompassed in protection scope of the present invention.
The below is with reference to the preferred embodiment of Fig. 3 description according to the cleaning method behind the wet etching of the present invention.
Please refer to Fig. 3, the cleaning method behind the wet etching of the present invention may further comprise the steps:
Step 301: after finishing the metallic aluminium wet-etching technology, carry out wet method removal first time silicon and consider to be worth doing residual.
Wherein, the metallic aluminium wet-etching technology is that the metallic aluminium on the thin oxide layer is carried out wet etching, it should be noted that thin oxide layer is very thin, its thickness is less than the spacing between the metal aluminum strip after the etching, so when wet etching is finished, oxide layer has been corroded totally, and silicon substrate also is corroded, and forms the silicon bits and separates out with residual.
The step of wet etching specifically comprises: at first, by applying photoresist layer, exposure, development etc. for the first time photoetching process form patterned photoresist at metallic aluminium, the thickness of photoresist layer can be 2 ~ 2.5 microns, and its type and thickness can be determined according to thickness and the best etching condition of metallic aluminium.
Then, carry out the photoresist oven dry, bake out temperature is 100 ℃ ~ 120 ℃, and drying time is 10 ~ 30 minutes; Carry out afterwards the photoresist dry ashing, podzolic gas is carbon tetrafluoride and oxygen, and the ashing time is 10 ~ 30 seconds.By photoresist oven dry and dry ashing, make photoresist have better adhesiveness and decay resistance, and can effectively improve surface configuration and the hydrophobic proterties of photoresist, thereby reduce the surface tension of the used wet etching liquid of etching metallic aluminium; Make in addition the photoresist corner become mellow and full, be conducive to the etching product and break away from, thus make the wet etching liquid more fully with Al Contact, reach even etching, reduce the purpose of metal residual.
Then, adopt the aluminium corrosive liquid that metallic aluminium is carried out wet etching take photoresist as mask, the composition of aluminium corrosive liquid comprises: 80% phosphoric acid, 5% nitric acid, 5% acetic acid and 10% water; Technological temperature is 35 to 45 ℃, and etch period can calculate according to the thickness of metallic aluminium and the etch rate of aluminium corrosive liquid.Afterwards, remove photoresist, the process gas of employing is oxygen, and the time is 30 ~ 90 minutes.
Because the isotropism of wet etching, and the spacing that is less than metal aluminum strip behind the wet etching of thin oxide layer in the present embodiment, the width of the groove that forms when that is to say the wet etching metallic aluminium, groove will run through thin oxide layer and extend to substrate, separate out with residual thereby make substrate produce the silicon bits.Therefore, according to cleaning method of the present invention, after finishing the metallic aluminium wet-etching technology, residual by the silicon bits that go silicon bits liquid to carry out on for the first time wet method removal substrate first.Go the composition of silicon bits liquid to comprise 60% ~ 70% phosphoric acid, 5% ~ 10% nitric acid, 10% ~ 20% acetic acid and 10% ~ 20% water; It is 23 ~ 25 ℃ that wet method is removed the technological temperature of silicon bits technique, and the time is 1 ~ 10 minute, and etch rate can remain
/ minute.Owing to behind the metallic aluminium wet etching, also can produce the accessory substance of some etchings, wet method is removed the residual effect that can play in the lump the cleaning accessory substance of silicon bits for the first time.In addition, the photoetching material of metallic aluminium remained on surface also can go the silicon bits to remove fully by wet method after photoresist was removed, thereby guarantee that when follow-up photoetching metallic aluminium surface can have the surface nature when being similar to for the first time photoetching, the live width of metal aluminum strip can not change yet.Yet, because wet method goes the process window of silicon bits technique not enough, after a wet method is removed the silicon bits, still have the silicon bits or white residue residual.
The condition of photoetching process is with for the first time identical for the second time, and it also comprises the photoresist gluing, exposure, and the processing step of development, the thickness of photoresist can be 2 ~ 2.5 microns.Masking layer when this layer photoetching glue goes silicon bits technique as follow-up wet method.
Drying condition is identical in the time of can be with the wet etching metallic aluminium, and bake out temperature is 100 ℃ ~ 120 ℃, and drying time is 10 ~ 30 minutes.
With the photoresist partial etching, with effective surface configuration and hydrophobic proterties of improving photoresist, go to go silicon to consider the surface tension of liquid to be worth doing in the silicon bits technique thereby reduce follow-up wet method.
Its process conditions can be removed silicon with the wet method first time and consider to be worth doing when residual identically, specifically, are to remove the silicon bits by going silicon bits liquid to carry out second time wet method, and the composition that goes silicon to consider liquid to be worth doing comprises 60% ~ 70% phosphoric acid, 5% ~ 10% nitric acid, 10% ~ 20% acetic acid and 10% ~ 20% water; Technological temperature is 23 ~ 25 ℃; Etch rate can remain
/ minute; Time is 1 ~ 10 minute, specifically determines according to the residual degree of white residue.Because photoresist covers the metallic aluminium surface as masking layer, play a protective role, therefore remove silicon and consider to be worth doing when residual carrying out second time wet method, can't corroding metal aluminium surperficial.
In order to prove technique effect of the present invention, chosen 3 kinds of technical schemes and tested experimental result such as following table 1:
Table 1
The result of experiment 1 shows, the time that increases the metallic aluminium wet-etching technology can't solve the residual problem of silicon bits, although the result of experiment 2 shows that increasing wet method goes the time of silicon bits technique can enlarge process window, reduce the residual quantity of silicon bits, but in the situation without photoresist masking, can cause damage to the metallic aluminium surface.And according to cleaning method of the present invention, carried out twice wet method to go silicon bits technique not only can enlarge wet method to remove silicon bits process window, it is residual effectively to reduce the silicon bits, and by photoetching process metallic aluminium is protected, and can keep the metallic aluminium surface nature constant.
By the invention described above preferred embodiment as can be known; the residual cleaning method of silicon bits is compared with traditional cleaning method behind the removal metallic aluminium wet-etching technology of the present invention; the steps such as photoetching metallic aluminium have been increased; with photoresist as masking layer; the protection metallic aluminium is unaffected when enlarging wet method to remove silicon bits process window; thereby can not produce charge accumulated and plasma damage; can guarantee reliability and the anti-radiation performance of device and products, to satisfy specialities to the requirement of high reliability and highly anti-radiation performance.In addition, the present invention is not only applicable to common product, is particularly useful for the product of thin oxide layer structure.
Although the present invention discloses as above with preferred embodiment; right described many embodiment only give an example for convenience of explanation; be not to limit the present invention; those skilled in the art can do some changes and retouching without departing from the spirit and scope of the present invention, and the protection range that the present invention advocates should be as the criterion so that claims are described.
Claims (9)
1. the cleaning method behind the wet etching is characterized in that, may further comprise the steps:
After finishing the metallic aluminium wet-etching technology, carry out wet method removal first time silicon and consider to be worth doing residual;
Form patterned photoresist by photoetching process at the metallic aluminium behind wet etching;
Carry out the photoresist oven dry;
Carry out the photoresist dry ashing;
It is residual to carry out wet method removal second time silicon bits.
2. the cleaning method behind the wet etching according to claim 1 is characterized in that, described metallic aluminium wet-etching technology may further comprise the steps:
Form patterned photoresist by photoetching process at described metallic aluminium;
Carry out the photoresist oven dry;
Carry out the photoresist dry ashing;
Take photoresist as mask, the described metallic aluminium of wet etching is to form groove, and described groove runs through the thin oxide layer of described metallic aluminium below and extends to substrate, and it is residual to make described substrate produce described silicon bits;
Remove described photoresist.
3. the cleaning method behind the wet etching according to claim 2 is characterized in that, the thickness of described thin oxide layer is less than the width of described groove.
4. the cleaning method behind the wet etching according to claim 1 and 2 is characterized in that, described photoetching process comprises the coating photoresist layer, exposure and development, and the thickness of wherein said photoresist layer is 2 to 2.5 microns.
5. the cleaning method behind the wet etching according to claim 1 and 2 is characterized in that, the temperature of carrying out the photoresist oven dry is 100 to 120 ℃, and the time is 10 to 30 minutes.
6. the cleaning method behind the wet etching according to claim 1 and 2 is characterized in that, the podzolic gas that carries out the photoresist dry ashing is carbon tetrafluoride and oxygen, and the ashing time is 10 to 30 seconds.
7. the cleaning method behind the wet etching according to claim 2 is characterized in that, by the described metallic aluminium of aluminium corrosive liquid wet etching, wherein said aluminium corrosive liquid composition comprises 80% phosphoric acid, 5% nitric acid, 5% acetic acid and 10% water; Technological temperature is 35 to 45 ℃.
8. the cleaning method behind the wet etching according to claim 2 is characterized in that, the process gas of removing described photoresist is oxygen, and the time is 30 to 90 minutes.
9. the cleaning method behind the wet etching according to claim 1 is characterized in that, and is residual by going silicon bits liquid wet method to remove the silicon bits, and the wherein said composition of silicon bits liquid that goes comprises 60% ~ 70% phosphoric acid, 5% ~ 10% nitric acid, 10% ~ 20% acetic acid and 10% ~ 20% water; Technological temperature is 23 to 25 ℃, and the time is 1 to 10 minute.
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| CN201210579772.6A CN103021817B (en) | 2012-12-27 | 2012-12-27 | Cleaning method after wet etching |
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Cited By (4)
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| CN104810279A (en) * | 2014-01-23 | 2015-07-29 | 北大方正集团有限公司 | Aluminum etching method and aluminum etching device |
| CN107342217A (en) * | 2017-07-18 | 2017-11-10 | 成都海威华芯科技有限公司 | A kind of processing method based on secondary wet process etching |
| CN110438504A (en) * | 2019-08-19 | 2019-11-12 | 江阴江化微电子材料股份有限公司 | A kind of alum gate Ke Kai area's silicon slag removes composition and silicon slag sweep-out method |
| CN110970313A (en) * | 2019-11-14 | 2020-04-07 | 长江存储科技有限责任公司 | Welding pad structure and preparation method of semiconductor structure |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107342217A (en) * | 2017-07-18 | 2017-11-10 | 成都海威华芯科技有限公司 | A kind of processing method based on secondary wet process etching |
| CN107342217B (en) * | 2017-07-18 | 2019-11-12 | 成都海威华芯科技有限公司 | A kind of processing method based on secondary wet process etching |
| CN110438504A (en) * | 2019-08-19 | 2019-11-12 | 江阴江化微电子材料股份有限公司 | A kind of alum gate Ke Kai area's silicon slag removes composition and silicon slag sweep-out method |
| CN110970313A (en) * | 2019-11-14 | 2020-04-07 | 长江存储科技有限责任公司 | Welding pad structure and preparation method of semiconductor structure |
| CN110970313B (en) * | 2019-11-14 | 2021-05-07 | 长江存储科技有限责任公司 | Welding pad structure and preparation method of semiconductor structure |
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