CN101562134B - Method for preparing tunnel window - Google Patents
Method for preparing tunnel window Download PDFInfo
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- CN101562134B CN101562134B CN2008100432635A CN200810043263A CN101562134B CN 101562134 B CN101562134 B CN 101562134B CN 2008100432635 A CN2008100432635 A CN 2008100432635A CN 200810043263 A CN200810043263 A CN 200810043263A CN 101562134 B CN101562134 B CN 101562134B
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- oxide film
- temperature oxidation
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Abstract
The invention discloses a method for preparing a tunnel window, which comprises the following steps: (1) coating an organic antireflective coating on a tunnel oxide film on a silicon chip matrix; (2) depositing a low-temperature oxide film layer on the organic antireflective coating; (3) coating photoresist on the low-temperature oxide film layer and photoetching; (4) carrying out plasma etching on the low-temperature oxide film layer so as to ensure that an open section of the low-temperature oxide film layer forms an inverse trapezoidal structure with the size of the lower part of an openingsmaller than that of the upper part; (5) carrying out the plasma etching on the antireflective coating and finally stopping the etching on the tunnel oxide film by completely consuming the photoresist; (6) opening the tunnel oxide film by utilizing a wet chemistry method and simultaneously removing the residual low-temperature oxide film; and (7) removing a residual organic antireflective coating. The method can reduce the key size of the tunnel window, reduce the cost and increase the profits.
Description
Technical field
The present invention relates to integrated circuit and make field, particularly a kind of method that in integrated circuit, prepares tunnel window.
Background technology
In some storage products, often need utilize tunnel window (Tunnel Window is called for short TW) structure.In the preparation of tunnel window, critical size is a size the most rambunctious in the preparation process.Reduce critical size can be on the unit silicon chip the more storage products of layout, thereby reduce manufacturing cost, improve profit.
The method flow of existing preparation tunnel window as shown in Figure 1.At first, barrier coating organic antireflective coating 3 and photoresist 5 successively on the tunnel oxidation rete 2 above the silicon chip matrix 1, and carry out the tunnel window photoetching, and form structure as shown in Figure 2, wherein, photoresist bottom critical size is 6.Then, as shown in Figure 3, open bottom antireflecting coating 3 by plasma etching industrial at the tunneling window oral region, at this moment, the bottom size of bottom antireflecting coating 3 is 7; Utilize wet chemical to open lower floor's tunnel oxidation rete 2 then, as shown in Figure 4, the tunnel oxidation rete bottom size of formation is 8; At last, as shown in Figure 5, remove remaining photoresist 5 and bottom antireflective coating 3, promptly obtain the tunnel window structure.
Open in lower floor's tunnel oxidation rete 2 technical processs at wet chemical, etching liquid is known from experience the lateral corrasion that causes tunnel oxide film 2 simultaneously, and the critical size 8 of final tunnel window is increased greatly.When lithographic dimensioned 6 remained unchanged, wet chemical was to the greatly requirement of further dwindling of arrowhead 8 of this increase effect meeting of the critical size 8 of tunnel window.
Prior art adopts two kinds of methods further to dwindle the critical size of tunnel window, and a kind of method is to adopt the relatively slow and metastable etching technics of etch rate of etch rate, can effectively control this degree to tunnel oxide film 2 lateral corrasions.But when residual photoresist 5 and anti-emission coating 3 thickness are bigger, perhaps the phenomenon of peeling off of photoresist hour takes place in photoresist line size easily in this wet chemical processing procedure.Therefore, generally this step wet chemical adopts the comparatively faster etching agent of etch rate more, as dilute hydrofluoric acid (DHF).This kind technology is difficult to the lateral corrasion control ratio of tunnel oxide film, and tunnel oxidation rete bottom size 8 increases more, and changes bigger.
Another kind method is by dwindling the lithographic dimensioned critical size that further dwindles tunnel window of tunnel window.Lithographic dimensionedly be subjected to the restrictions such as mask aligner, photoresist type and thickness, antireflecting coating material type and thickness adopted, and photoresist thickness also is subjected to the restriction of tunnel window etching process.When photoresist thickness was big, the photoresist size was difficult to do very for a short time.
Existing technology is difficult to solve the problem that has increased the tunnel window critical size in the preparation tunnel window technology owing to the influence of various factors.
Summary of the invention
Technical problem to be solved by this invention provides a kind of method for preparing tunnel window, not only make the phenomenon that photoresist lift off can not take place in preparation process, simultaneously can reduce of the increase effect of wet chemical technology to the tunnel window size as far as possible, thereby reduce the critical size of tunnel window, reduce cost, increase profit.
For solving the problems of the technologies described above, the technical scheme of method for preparing tunnel window of the present invention is may further comprise the steps:
The first step is coated with organic antireflective coating on the tunnel oxidation rete on the silicon chip matrix;
Second step, deposit low-temperature oxidation rete on organic antireflective coating; The deposition temperature of described low-temperature oxidation rete is lower than 300 ℃;
In the 3rd step, on the low-temperature oxidation rete, be coated with photoresist, and carry out photoetching;
The 4th step, the low-temperature oxidation rete is carried out plasma etching, make low-temperature oxidation film open section present the size inverted trapezoidal structure littler of lower opening portion than upper dimension;
In the 5th step, the antagonistic reflex coating is carried out plasma etching, and this etching finally stops on the tunnel oxidation rete, and with the photoresist full consumption;
The 6th step, utilize wet chemical to open tunnel oxide film, remove remaining low-temperature oxidation film simultaneously;
In the 7th step, remove remaining organic antireflective coating.
Be that the low-temperature oxidation thicknesses of layers of institute's deposit is between 2 times to 4 times of tunnel oxidation thicknesses of layers in second step as a further improvement on the present invention.
Be in the 4th step the low-temperature oxidation film to be carried out the angle of the open section that forms behind the plasma etching between 30 to 60 degree as another kind of further improvement of the present invention.
The present invention is deposit one deck low-temperature oxidation film on organic antireflective coating, when opening the low-temperature oxidation film, plasma etching make low-temperature oxidation film open section present the size inverted trapezoidal structure littler of lower opening portion then than upper dimension, the relative tunnel key size during photoetching, the bottom size of trapezoidal low-temperature oxidation film opening of falling has obtained dwindling, the oxide-film lateral corrasion that the etching process of stabilize etch rates causes in wet chemical subsequently is also less, so the present invention's littler TW critical size of size can finally obtain than photoetching the time.
Description of drawings
The present invention is further detailed explanation below in conjunction with drawings and Examples:
Fig. 1 is a prior art tunnel window preparation technology schematic flow sheet;
Fig. 2 to Fig. 5 is the structural representation of prior art for preparing tunnel window technological process correspondence;
Fig. 6 is a schematic flow sheet of the present invention;
Fig. 7 to Figure 11 is the structural representation of preparation technology's flow process correspondence of the present invention.
Embodiment
As shown in Figure 6, embodiment of the invention method for preparing tunnel window comprises following step:
At first, on the tunnel oxidation rete on the silicon chip matrix, be coated with organic antireflective coating, the tunnel oxidation film thickness 80 to
Between, the type of antireflecting coating and thickness are selected according to etching condition, general anti-reflective coating layer thickness 300 to
Between.
Secondly, deposit one deck low-temperature oxidation rete on organic antireflective coating, its thickness are between 2 times to 4 times of tunnel oxidation thicknesses of layers, generally 200 to
Between, the deposition temperature of deposit low-temperature oxidation rete is lower than 300 ℃.
The 3rd step was coated with photoresist, and carries out photoetching on the low-temperature oxidation rete, obtain structure as shown in Figure 7, and 6 is the critical size of photoresist bottom.Can select suitable exposure machine type and photoresist type according to final critical size requirement herein.Select the thickness of suitable photoresist according to etching condition.And owing to carry out in the plasma etching industrial in follow-up antireflecting coating, above-mentioned photoresist can be fallen by full consumption, so do not need to consider the requirement of wet processing to photoresist thickness.
The 4th step, as shown in Figure 8, the low-temperature oxidation rete is carried out plasma etching, make low-temperature oxidation film open section present the size inverted trapezoidal structure littler of lower opening portion than upper dimension, and the opening angle of section is between 30 to 60 degree, wherein, 6 is the critical size of photoresist bottom, and 9 is low-temperature oxidation film bottom critical size.Generally general employing of low-temperature oxidation film etching contained C, F gas, in order to obtain down trapezoidal oxide-film section, the present invention adopts some can increase sedimental gas system.As adopt CHF
3, CH
2F
2, C
4F
6, C
4F
8Perhaps C
5F
8Deng, and add Ar, N simultaneously
2, gas such as CO.And the technological parameter of band plasma etching is as follows: the radio-frequency power that is adopted when carrying out plasma etching is 500 to 1100W, and cavity internal pressure is 25 to 120mT, and total gas flow rate is 100 to 300sccm, wherein CHF
3Perhaps CH
2F
2Flow is 0 to 120sccm, C
4F
6, C
4F
8And C
5F
8Deng total gas flow rate is 2 to 40sccm, CHF
3, CH
2F
2, C
4F
6, C
4F
8And C
5F
8Deng total gas flow rate is 10 to 60sccm, and the Ar gas flow is 20 to 180sccm, N
2With gas flows such as CO be 0 to 150sccm.In the present embodiment, by increasing N
2, CHF
3, CH
2F
2, C
4F
6, C
4F
8And C
5F
8Can increase the gradient of low-temperature oxidation film open section after the etching Deng gas flow, promptly increase the difference of the trapezoidal upper and lower size of opening, reduce low-temperature oxidation film bottom critical size with this.
In the 5th step, as shown in Figure 9, adopt Cl
2, HBr, O
2Etc. gas system, perhaps adopt CF
4, CHF
3Contain gas system antagonistic reflex coatings such as C, F and carry out plasma etching, this etching finally stops on the tunnel oxidation rete, and with the photoresist layer full consumption, wherein, 10 critical sizes for bottom antireflective coating bottom among the present invention.Utilize dijection frequency power etching machine when the antagonistic reflex coating is carried out plasma etching, source power is 200 to 600W, and deflection power is 30 to 300W, and gas pressure is 2 to 20mT, and total gas couette is 50 to 250sccm, and the Ar flow is 0 to 180sccm, when adopting Cl
2, HBr, O
2During etc. gas system, Cl
2Flow is 0 to 100sccm, O
2Flow is 0 to 50sccm, when adopting CF
4, CHF
3When containing gas system such as C, F, CF
4Flow is 0 to 150sccm, CHF
3Waiting other to contain C, F gas flow is 0 to 100sccm, and deflection power that adopts in the present embodiment and gas composition can realize stronger anisotropic etching, reduce the lateral corrasion amount to material.
The 4th above-mentioned step can be undertaken by different equipment respectively with the 5th step, also can finish on same equipment.
The 6th step, as shown in figure 10, utilize wet chemical to open tunnel oxide film, remove remaining low-temperature oxidation film simultaneously, wherein, 11 are tunnel oxide film bottom critical size among the present invention.Because photoresist layer is eliminated fully, therefore there is not the photoresist lift off problem in the 5th step.Can adopt the slower buffer oxide film etching agent of speed (Bufferedoxide etcher, be called for short BOE) when utilizing wet chemical to open tunnel oxide film, and to the etch rate of tunnel oxide film less than
Can guarantee the uniformity of etching like this, effectively control the side direction etching.Buffer oxide film etching agent may reach to the tunnel oxide film etch rate about 2 to 5 times to the etching speed of low-temperature oxidation film.In this process, the low-temperature oxidation film is removed fully, and following antireflecting coating is come out fully.
At last, as shown in figure 11, can the using plasma ashing etc. method remove remaining organic antireflective coating, obtain the less tunnel window of final critical size.
The present invention is by deposit one deck low-temperature oxidation film on antireflecting coating, can increase sedimental gas system and when using plasma is opened the low-temperature oxidation rete, adopt, make low-temperature oxidation film open section after the etching little trapezoidal below big above presenting, and when opening tunnel oxide film, adopts wet chemical subsequently the slower buffer oxide film etching agent of speed, effectively control the side direction etching, thereby reduced the critical size of tunnel window.In addition, adopt the inventive method, need not to consider the problem of photoresist lift off.Therefore the present invention's method of preparing tunnel window has reduced production cost, raises the efficiency.
Claims (9)
1. a method for preparing tunnel window is characterized in that, may further comprise the steps:
The first step is coated with organic antireflective coating on the tunnel oxidation rete on the silicon chip matrix;
Second step, deposit low-temperature oxidation rete on organic antireflective coating; The deposition temperature of described low-temperature oxidation rete is lower than 300 ℃;
In the 3rd step, on the low-temperature oxidation rete, be coated with photoresist, and carry out photoetching;
The 4th step, the low-temperature oxidation rete is carried out plasma etching, make low-temperature oxidation film open section present the size inverted trapezoidal structure littler of lower opening portion than upper dimension;
In the 5th step, the antagonistic reflex coating is carried out plasma etching, and this etching finally stops on the tunnel oxidation rete, and with the photoresist full consumption;
The 6th step, utilize wet chemical to open tunnel oxide film, remove remaining low-temperature oxidation film simultaneously;
In the 7th step, remove remaining organic antireflective coating.
2. method for preparing tunnel window according to claim 1 is characterized in that, the low-temperature oxidation thicknesses of layers of institute's deposit is between 2 times to 4 times of tunnel oxidation thicknesses of layers in second step.
3. method for preparing tunnel window according to claim 2 is characterized in that, the low-temperature oxidation thicknesses of layers of institute's deposit 200 to
Between.
4. method for preparing tunnel window according to claim 1 is characterized in that, in the 4th step the low-temperature oxidation film is carried out the angle of the open section that forms behind the plasma etching between 30 to 60 degree.
5. method for preparing tunnel window according to claim 1 is characterized in that, the plasma etching employing in the 4th step can increase sedimental gas system and carry out.
6. method for preparing tunnel window according to claim 5 is characterized in that: described can to increase sedimental gas system be CHF
3, CH
2F
2, C
4F
6, C
4F
8Perhaps C
5F
8, and add Ar, N simultaneously
2, CO gas.
7. method for preparing tunnel window according to claim 6, it is characterized in that the radio-frequency power that is adopted when in the 4th step the low-temperature oxidation film being carried out plasma etching is 500 to 1100W, cavity internal pressure is 25 to 120mT, total gas flow rate is 100 to 300sccm, wherein CHF
3Flow is 0 to 120sccm or CH
2F
2Flow is 0 to 120sccm, and the Ar gas flow is 20 to 180sccm, N
2Gas flow be 0 to 150sccm and the gas flow of CO be 0 to 150sccm.
8. method for preparing tunnel window according to claim 1 is characterized in that, adopts Cl when the antagonistic reflex coating is carried out plasma etching in the 5th step
2, HBr, O
2Gas system perhaps adopts CF
4, CHF
3Contain C, F gas system.
9. method for preparing tunnel window according to claim 8, it is characterized in that, utilize dijection frequency power etching machine when the antagonistic reflex coating is carried out plasma etching in the 5th step, source power is 200 to 600W, deflection power is 30 to 300W, and gas pressure is 2 to 20mT, and total gas couette is 50 to 250sccm, the Ar flow is 0 to 180sccm, when adopting Cl
2, HBr, O
2During gas system, Cl
2Flow is 0 to 100sccm, O
2Flow is 0 to 50sccm, when adopting CF
4, CHF
3When containing the gas system of C, F, CF
4Flow is 0 to 150sccm, CHF
3Flow is 0 to 100sccm.
9. method for preparing tunnel window according to claim 1 is characterized in that, wet chemical adopts the slower buffer oxide film etching agent of speed when opening tunnel oxide film in the 6th step, and to the etch rate of tunnel oxide film less than
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|---|---|---|---|
| CN2008100432635A CN101562134B (en) | 2008-04-17 | 2008-04-17 | Method for preparing tunnel window |
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|---|---|---|---|
| CN2008100432635A CN101562134B (en) | 2008-04-17 | 2008-04-17 | Method for preparing tunnel window |
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| CN101562134B true CN101562134B (en) | 2011-12-14 |
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| CN102194734A (en) * | 2010-03-12 | 2011-09-21 | 中芯国际集成电路制造(上海)有限公司 | Method for enlarging metal interconnected lithography process window |
| CN102122641B (en) * | 2011-01-27 | 2015-02-25 | 上海华虹宏力半导体制造有限公司 | Method for forming one time programmable (OTP) device |
| CN103137441A (en) * | 2011-11-22 | 2013-06-05 | 上海华虹Nec电子有限公司 | Method for manufacturing elongated isolated line pattern in semiconductor process |
| CN108751123B (en) * | 2018-05-21 | 2022-05-20 | 赛莱克斯微系统科技（北京）有限公司 | Method for forming contact window |
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Owner name: SHANGHAI HUAHONG GRACE SEMICONDUCTOR MANUFACTURING Free format text: FORMER OWNER: HUAHONG NEC ELECTRONICS CO LTD, SHANGHAI Effective date: 20140107 |
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Free format text: CORRECT: ADDRESS; FROM: 201206 PUDONG NEW AREA, SHANGHAI TO: 201203 PUDONG NEW AREA, SHANGHAI |
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Effective date of registration: 20140107 Address after: 201203 Shanghai city Zuchongzhi road Pudong New Area Zhangjiang hi tech Park No. 1399 Patentee after: Shanghai Huahong Grace Semiconductor Manufacturing Corporation Address before: 201206, Shanghai, Pudong New Area, Sichuan Road, No. 1188 Bridge Patentee before: Shanghai Huahong NEC Electronics Co., Ltd. |