CN101728317B - Forming methods of conducting structure and pad - Google Patents
Forming methods of conducting structure and pad Download PDFInfo
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- CN101728317B CN101728317B CN200810224804.4A CN200810224804A CN101728317B CN 101728317 B CN101728317 B CN 101728317B CN 200810224804 A CN200810224804 A CN 200810224804A CN 101728317 B CN101728317 B CN 101728317B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
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- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Abstract
The invention discloses a forming method of a conducting structure. The forming method comprises the following steps of: providing a substrate with a lower conducting structure; sequentially forming an etching stop layer and an interlayer dielectric layer on the substrate; defining a conducting structure opening graph on the interlayer dielectric layer; etching the interlayer dielectric layer to form a conducting structure opening by using the conducting structure opening graph as a mask; etching the etching stop layer at the bottom of the conducting structure opening, wherein the added oxygen flow rate is between 15sccm and 25sccm in the etching process; and filling metal into the conducting structure opening so as to form the conducting structure. The invention also discloses a forming method of a pad. By utilizing the forming methods of the conducting structure and the pad, the forming quality of the conducting structure or the pad can be improved so as to effectively improve the electrical property of devices.
Description
Technical field
The present invention relates to technical field of manufacturing semiconductors, particularly a kind of formation method of conductive structure and pad.
Background technology
The making of semiconductor integrated circuit is extremely complicated process, its object is required particular electrical circuit various electronic building bricks and circuit, dwindle on the silicon chip that is produced on small size, and each assembly must be electrically connected by suitable internal connecting line the function that competence exertion is desired.
Along with the making of integrated circuit develops to very lagre scale integrated circuit (VLSIC) (ULSI), inner current densities is increasing, contained number of elements constantly increases, and makes the surface of wafer cannot provide enough areas to make required interconnection line (Interconnect).Therefore,, for co-operating member dwindles rear increased interconnection line demand, the design of two-layer above multiple layer metal interconnection line, just becomes the method that very large scale integration technology institute must employing.At present, the conducting of (or between bottom transistor AND gate metal interconnecting wires) between different metal layer, be by digging an opening and insert electric conducting material at the insulating barrier of (or between bottom transistor AND gate metal interconnecting wires) between two metal layers, form the various conductive structures (as contact hole, through hole or dual-damascene structure) of conducting two metal levels and realize.The formation quality of this conductive structure is very large for the performance impact of circuit, if the formation of conductive structure is second-rate, can cause circuit overall resistance to rise, and when serious, device is by cisco unity malfunction.
Fig. 1 is explanation existing a kind of conductive structure---the device profile schematic diagram of through hole to Fig. 4.Wherein, Fig. 1 is the device profile schematic diagram forming in existing forming process of through hole after interlayer dielectric layer, as shown in Figure 1, has formed lower floor's conductive structure 110 in substrate 100, in order to realize being electrically connected between this layer of circuit and upper strata circuit, need to form through hole thereon.Conventionally, one deck etching stop layer 101 of first growing on substrate 100, it can be silicon nitride layer or silicon carbide layer.The etch rate of this etching stop layer 101 will be starkly lower than interlayer dielectric layer 102, can stop at comparatively equably in this etching stop layer 101 when the etching through hole opening guaranteeing.Then, on this etching stop layer 101 regrowth for the interlayer dielectric layer 102 of interlayer electric insulation.
Fig. 2 is the device profile schematic diagram forming in existing forming process of through hole after via hole image, as shown in Figure 2, utilizes photoetching process to define via hole image 105 on interlayer dielectric layer 102 surfaces.
Fig. 3 is the device profile schematic diagram forming in existing forming process of through hole after via openings, as shown in Figure 3, defines with photoresist after via hole image 105, can utilize dry etching technology at the interior formation via openings 107 of interlayer dielectric layer 102.Because the etch rate of the etching stop layer 101 of lower floor will be much smaller than the etch rate of interlayer dielectric layer 102, this step etching can stop in etching stop layer 101.
Fig. 4 is the device profile schematic diagram of removing in existing forming process of through hole after etching stop layer, as shown in Figure 4, after interlayer dielectric layer 102 etchings complete, also need etching stop layer 101 residual via openings 107 bottoms to remove, to expose lower floor's conductive structure 110 to the open air, this step conventionally can be described as stop-layer and removes step (LRM, Liner Removal).
The LRM step of this step normally utilizes dry etch process to realize, in practical operation, the more difficult control of this step etching process, often there are some defects: as depression problem (undercut or pull back) appears in the side-walls at etching stop layer (being through-hole side wall below place), as caved in Fig. 4 as shown in the of 120; Or etching stop layer 101 is not completely removed, lower floor's conductive structure 110 such as does not expose completely to the open air at the problem.Fig. 5 is the device profile map that occurs depression problem while utilizing existing formation method to form through hole in side-walls, as shown in Figure 5, has occurred depression 510 at the sidewall at etching stop layer place.
Especially in the following technology node of 65nm, etching stop layer 101 is formed by the carborundum of comparatively weak nitrating conventionally, and it is more strict to the requirement of technology controlling and process, and this step etching occurs that the problem of above-mentioned defect is also even more serious.Once and there is such defect problem, will directly have influence on the formation quality of through hole (or saying conductive structure) below, and then have influence on the electrical connection quality in integrated circuit, make the degradation of device even lose efficacy.
The Chinese patent application that disclosed publication number was CN101231968A on July 30th, 2008 discloses a kind of inlaying inner connecting line structure and dual-damascene technics, it utilizes carbon tetrafluoride and nitrogen trifluoride gas bulk plasmon is the etching gas in LRM, to solve the problem that forms groove in layer dielectric layer causing due to misalignment in mosaic texture.But this application does not propose effective solution for above-mentioned because of the improper problem that occurs defect in conductive structure of LRM step control.
Summary of the invention
The invention provides a kind of formation method of conductive structure and pad, to improve the phenomenon that is prone to defect in existing conductive structure or pad.
For achieving the above object, the formation method of a kind of conductive structure provided by the invention, comprises step:
The substrate that forms lower floor's conductive structure is provided;
On described substrate, form successively etching stop layer and interlayer dielectric layer;
On described interlayer dielectric layer, define conductive structure opening figure;
Taking described conductive structure opening figure as mask, interlayer dielectric layer forms conductive structure opening described in etching;
The etching stop layer of conductive structure open bottom described in etching, and the oxygen flow adding in described etching process is between 15sccm to 25sccm, so that the sidewall shape of conductive structure opening is good;
In described conductive structure opening, fill metal, form conductive structure.
Wherein, after etching is removed described etching stop layer, also described substrate has been carried out to in-situ hydrogen plasma treatment.
The present invention has the formation method of the another kind of pad of identical or relevant art feature, comprises step:
The substrate that forms lower floor's conductive structure is provided;
On described substrate, form etching stop layer;
On described etching stop layer, form passivation layer;
On described passivation layer, define bonding pad opening figure;
Taking described bonding pad opening figure as mask, passivation layer forms bonding pad opening described in etching;
The etching stop layer of bonding pad opening bottom described in etching, and the oxygen flow adding in described etching process is between 15sccm to 25sccm, so that the sidewall shape of bonding pad opening is good;
Covering aluminum metal in described bonding pad opening, forms pad.
Wherein, after etching is removed described etching stop layer, also described substrate has been carried out to in-situ hydrogen plasma treatment.
Compared with prior art, the present invention has the following advantages:
The formation method of conductive structure of the present invention and pad, the etching technics during to removal etching stop layer is optimized, and uses oxygen to replace traditional hydrogen as etching gas, and oxygen flow is strictly limited between 15 to 25sccm.Make on the one hand interlayer dielectric layer or passivation layer more suitable than with the selection of etching stopping interlayer, can also utilize on the other hand oxygen number to polymer in etching process to adjust, guarantee to obtain the sidewall shape of more preferably conductive structure opening or bonding pad opening from above-mentioned two aspects.In addition, can also utilize oxygen in etching, to remove partial polymer, making only has a small amount of polymer deposition in open bottom in etching process or does not substantially have, thereby obtains more clean conductive structure opening or bonding pad opening.Utilize the formation method of conductive structure of the present invention and pad, can improve the formation quality of conductive structure or pad, effectively improve the electrical property of device.
In one of them embodiment of the formation method of conductive structure of the present invention and pad, also after removing etching stop layer, etching adds in-situ hydrogen plasma treatment step, deoxidation processing is carried out on surface to lower floor's conductive structure that may be partially oxidized in etching process, further improve the formation quality of conductive structure or pad, further improved the electrical property of device.
brief description of the drawings
Fig. 1 is the device profile schematic diagram forming in existing forming process of through hole after interlayer dielectric layer;
Fig. 2 is the device profile schematic diagram forming in existing forming process of through hole after via hole image;
Fig. 3 is the device profile schematic diagram forming in existing forming process of through hole after via openings;
Fig. 4 is the device profile schematic diagram of removing in existing forming process of through hole after etching stop layer;
Fig. 5 is the device profile map that occurs depression problem while utilizing existing formation method to form through hole in side-walls;
Fig. 6 is the flow chart of the method for forming via of explanation first embodiment of the invention;
Fig. 7 to Fig. 9 is the device profile schematic diagram of the method for forming via of explanation first embodiment of the invention;
Figure 10 is the flow chart of the bonding pad forming method of explanation second embodiment of the invention;
Figure 11 to Figure 16 is the device profile schematic diagram of the bonding pad forming method of explanation second embodiment of the invention;
Figure 17 is the bonding pad opening profile that utilizes second embodiment of the invention method to form.
Embodiment
For above-mentioned purpose of the present invention, feature and advantage can be become apparent more, below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in detail.
Processing method of the present invention can be widely used in every field; and can utilize many suitable materials to make; to be illustrated by specific embodiment below; certainly the present invention is not limited to this specific embodiment, and the known general replacement of one of ordinary skilled in the art is encompassed in protection scope of the present invention far and away.
Secondly, the present invention utilizes schematic diagram have been described in detail, in the time that the embodiment of the present invention is described in detail in detail, for convenience of explanation, the profile that represents device architecture can be disobeyed local amplification of general ratio work, should be using this as limitation of the invention, in addition, in actual making, should comprise the three-dimensional space of length, width and the degree of depth.
In order to improve the formation quality of conductive structure (or pad), the present invention improves the formation method of conductive structure (or pad), has proposed a kind of formation method of conductive structure, comprises step:
The substrate that forms lower floor's conductive structure is provided;
On described substrate, form successively etching stop layer and interlayer dielectric layer;
On described interlayer dielectric layer, define conductive structure opening figure;
Taking described conductive structure opening figure as mask, interlayer dielectric layer forms conductive structure opening described in etching;
The etching stop layer of conductive structure open bottom described in etching, and the oxygen flow adding in described etching process is between 15sccm to 25sccm;
In described conductive structure opening, fill metal, form conductive structure.
The flow of the carbon containing fluorine gas wherein, adding in described etching process is between 30sccm to 80sccm.And in described etching process, also added inert gas, the flow of described inert gas can be between 150sccm to 250sccm.
Wherein, after etching is removed described etching stop layer, also carried out in-situ hydrogen plasma treatment, and the flow that passes into hydrogen when described in-situ hydrogen plasma treatment is between 300sccm to 800sccm.
Wherein, the chamber pressure in described etching and in-situ hydrogen plasma treatment procedure is between 5mTorr to 20mTorr.
A kind of formation method that the invention allows for pad, comprises step:
The substrate that forms lower floor's conductive structure is provided;
On described substrate, form etching stop layer;
On described etching stop layer, form passivation layer;
On described passivation layer, define bonding pad opening figure;
Taking described bonding pad opening figure as mask, passivation layer forms bonding pad opening described in etching;
The etching stop layer of bonding pad opening bottom described in etching, and the oxygen flow adding in described etching process is between 15sccm to 25sccm;
Covering aluminum metal in described bonding pad opening, forms pad.
The flow of the carbon containing fluorine gas wherein, adding in described etching process is between 30sccm to 80sccm.
Wherein, after etching is removed described etching stop layer, also described substrate is carried out to in-situ hydrogen plasma treatment, when described in-situ hydrogen plasma treatment, passed into the flow of hydrogen between 300sccm to 800sccm.
Wherein, the chamber pressure in described etching and in-situ hydrogen plasma treatment procedure is between 5mTorr to 20mTorr.
The conductive structure that the present invention proposes or the formation method of pad are mainly that the step (LRM step) to wherein removing etching stop layer has been carried out process optimization, change the hydrogen passing in conventional method into oxygen, and the flow of oxygen is strict controlled in to 15 to 25sccm, the sidewall shape that realizes conductive structure opening (or bonding pad opening) is good, residual polyalcohol is less, and then realizes the raising of conductive structure (or pad) formation quality.
Conductive structure in the present invention specifically can comprise various structures, as any in contact hole, through hole or dual-damascene structure etc.Introduce in detail the detailed process of utilizing conductive structure formation method of the present invention to form through hole below by the first embodiment.
The first embodiment:
Fig. 6 is the flow chart of the method for forming via of explanation first embodiment of the invention, and Fig. 7 to Fig. 9 is the device profile schematic diagram of the method for forming via of explanation first embodiment of the invention, below in conjunction with Fig. 6 to Fig. 9, the first embodiment of the present invention is elaborated.
Step 601: the substrate that forms lower floor's conductive structure is provided.
In the present embodiment, in substrate, established lower floor conductive structure is copper metal connection structure, and it can be connected with the metal connection structure that descends again one deck, also can be connected with the conductive structure of the metal oxide semiconductor transistor of lower floor.
Step 602: form successively etching stop layer and interlayer dielectric layer on described substrate.
Fig. 7 forms the device profile schematic diagram after interlayer dielectric layer in the method for forming via of first embodiment of the invention, as shown in Figure 7, in substrate 700, form lower floor's conductive structure 710, on the substrate that has formed lower floor's conductive structure 710, formed successively again etching stop layer 701 and interlayer dielectric layer 702.
Because the etch rate between the different region of device closeness and between central area and fringe region has bigger difference; Or because of etching remove each layer deposit time there is consistent situation in uneven thickness, all can cause the etching result of zones of different on same substrate inconsistent.For fear of the problems referred to above, while guaranteeing below etching interlayer dielectric layer 702, can obtain the comparatively etching result of uniformity, can before deposition interlayer dielectric layer 702, first on substrate, form one deck etching stop layer 701.The material require that this etching stop layer 701 is selected is different from the material that the interlayer dielectric layer 702 forming is thereafter selected, and etch rate wants much slow.
In the present embodiment, interlayer dielectric layer 702 has been selected the silica material of low-k, as, can be black diamond (BD) material, etching stop layer 701 can be selected the materials such as silicon nitride, silicon oxynitride or carborundum.Specifically in the present embodiment, select silicon nitride material, it has lower etch rate under the etching condition of silica, can guarantee the etching energy of interlayer dielectric layer 702 comparatively to stop in etching stop layer 701 uniformity, prevents that lower floor's conductive structure 710 from sustaining damage.
Under normal circumstances, the thickness of etching stop layer 701 can be arranged on
extremely
between, the thickness of interlayer dielectric layer 702 at least need to be
above, as
deng.Wherein, the etching depth of the setting of the thickness of concrete etching stop layer 701, interlayer dielectric layer 702 poor with the etch rate of itself and interlayer dielectric layer 702 etc. is relevant.When the etching depth of the poor large or interlayer dielectric layer 702 of the two etch rate hour, can the thickness of etching stop layer 701 be arranged littlely, otherwise need to arrange greatlyr.
Step 603: define via openings figure on described interlayer dielectric layer.
On interlayer dielectric layer 702, cover photoresist, recycling photoetching process forms via openings figure.
Step 604: taking described via openings figure as mask, interlayer dielectric layer forms via openings described in etching.
Fig. 8 forms the device profile schematic diagram after via openings in the method for forming via of first embodiment of the invention, and as shown in Figure 8, the via openings figure that utilizes photoresist to form is mask, and etching interlayer dielectric layer 702, forms via openings 707 therein.Because the etch rate of etching stop layer 701 will be much smaller than the etch rate of interlayer dielectric layer 702, this step etching can stop in etching stop layer 701.
After this step etching completes, on substrate, common meeting residual fraction photoresist 705 also can adhere to some polymer on via openings 707 sidewalls that form.Then, can remove the operation of the polymer (not shown) producing in residual photoresist 705 and this step etching.This operation can utilize microwave to carry out under higher temperature conventionally, also can utilize special ashing resist remover to carry out.
Removing after residual photoresist 705, can also add a step wet clean step, to remove photoresist residue and residual polymer.This cleaning operation can utilize SC1 cleaning fluid to complete.
Step 605: the etching stop layer of via openings bottom described in etching, and the oxygen flow adding in described etching process is between 15 to 25sccm.
This step etching can utilize inductively coupled plasma etching machine (Inductive CoupledPlasma, ICP) to complete.
In the present embodiment, in order to overcome the defect being prone in through hole in prior art, etching mechanism is conducted in-depth analysis.Think and occur that the reason of defect is in prior art, to utilize carbon containing fluorine gas and hydrogen as etching gas; although add hydrogen can increase to a certain extent the selection ratio between interlayer dielectric layer 702 and etching stop layer 701 in etching process; but; the polymer that it produces conventionally can cause etching time etc. is difficult to remove; make the via openings of formation second-rate, device electrical performance is also subject to obvious impact.
For this reason, use oxygen to replace traditional hydrogen as etching gas in the present embodiment, but adopt after oxygen, the more difficult control of selection between interlayer dielectric layer 702 and etching stop layer 701, is prone to defect.
In prior art, the flow that passes into oxygen in etching conventionally can be less or larger, and as passed into sometimes a small amount of oxygen when the materials such as etch silicon nitride, its conventional flow is also only in 10sccm left and right, even less, to obtain larger etch rate.But experiment is found, in the time removing etching stop layer 701, if flow of oxygen is less, the etch rate of etching stop layer 701 (being silicon nitride material in the present embodiment) can be crossed faster than interlayer dielectric layer 702 (being silica material in the present embodiment), therefore, if adopt the conventional amount used of existing etch silicon nitride, can form the depression 510 shown in Fig. 5.
In addition, in prior art, in the time that removing photoresist, etching conventionally can select larger oxygen flow, as more than hundreds of sccm.But find in practical operation, if flow of oxygen is too many, the etch-rate of silicon nitride can be less than silica, now, removed by complete etching in order to ensure the silicon nitride material as etching stop layer 701, having the interlayer dielectric layer 702 more being formed by silica material is removed and (notices now and there is no photoresist protection on interlayer dielectric layer 702, it can lose more), and the thickness of interlayer dielectric layer 702 has requirement, can not be excessively thin, this can only arrange less over etching rate (ratio between over etching time and main etching time) while just making etching remove etching stop layer 701, result be easy to cause having partial through holes not etching put in place, make through hole resistance value larger, device electrical performance is poor.
But after experimental analysis, if find to adopt a certain oxygen flow among a small circle still can obtain satisfied result.As, oxygen flow is strictly limited between 15 to 25sccm, can obtain the etching selection ratio between comparatively suitable interlayer dielectric layer 702 and etching stop layer 701 on the one hand, on the other hand can also because of introduce oxygen realize in etching process to polymer number adjustment, thereby guaranteed to obtain more preferably via openings from above-mentioned two aspects.
In addition, can also utilize oxygen in etching, to remove partial polymer, making only has a small amount of polymer deposition in open bottom in etching process or does not substantially have, thereby obtains more clean via openings.Utilize the method for forming via in the present embodiment, can improve the formation quality of through hole, effectively improve the electrical property of device.
The condition of work of this step etching after optimization can be set to: substrate to be etched is put into plasma etching equipment, vacuumize, pass into etching gas and assist gas, at room temperature (be generally 25 DEG C of left and right) and carry out plasma etching treatment.Wherein, chamber pressure can be arranged between 5 to 20mTorr, as is 5mTorr, 10mTorr, 15mTorr or 20mTorr etc.; Etching power adjustments to 200 is between 600W, as is 200W, 300W, 400W or 600W etc.
The oxygen flow passing in etching process is strict controlled between 15 to 25sccm, as is 15sccm, 18sccm, 22sccm or 25sccm etc.The etching gas of the carbon containing fluorine simultaneously passing into, as CF
4, CF
8, C
5f
8, C
4f
6, CHF
3between 30 to 80sccm, as be 30sccm, 40sccm, 50sccm, 60sccm, 70sccm or 80sccm etc. Deng, flow set.
In the present embodiment, this stage has also added assist gas, and as argon gas, its flow can be between 150 to 250sccm, as are 150sccm, 180sccm, 200sccm or 250sccm etc.This assist gas can regulate the concentration of etching gas in chamber on the one hand, and then changes etch rate; The pressure that also can be used for adjusting on the other hand chamber, makes it remain on set point.
Fig. 9 removes the device profile schematic diagram after etching stop layer in the method for forming via of first embodiment of the invention, as shown in Figure 9, remove after etching stop layer 701, residual photoresist 705 is removed originally, and the etching stop layer 701 of via openings 707 bottoms is removed.
Remove after etching stop layer 701 in etching, in the present embodiment, also add the hydrogen plasma treatment step of a step original position, deoxidation processing is carried out on surface with the lower floor's conductive structure 710 to may be partially oxidized in etching process, further improves the formation quality of through hole.
In the present embodiment, this step is as follows with the process conditions of the in-situ hydrogen plasma treatment step that removal etching stop layer 701 completes in same etching apparatus: maintain the temperature-resistant of chamber, chamber pressure still can be arranged between 5 to 20mTorr, etching power also can with keep on last stage identical, as can be still remained between 200 to 600W, as be 200W, 300W, 400W or 600W etc.The etching gas that stops passing on last stage and assist gas, change into and only pass into hydrogen, and its flow can be arranged between 300 to 800sccm, as be 300sccm, 500sccm, 600sccm or 800sccm etc.
In the present embodiment, in the time that etching is removed etching stop layer 701, can also add certain bias voltage (bias power), to make the bombardment of the plasma in chamber there is certain directivity, improve the efficiency (this bias voltage can be arranged between 100 to 200W conventionally) of removing photoresist or etching stop layer.And in the time carrying out hydrogen plasma processing, via openings 707 bottoms have exposed lower floor's conductive structure 710, and its object is only to utilize hydrogen plasma to carry out deoxidation processing to these lower floor's conductive structure 710 surfaces.For preventing that hydrogen plasma damage from having exposed lower floor's conductive structure 710 outside to the open air, in the present embodiment, do not apply bias voltage in this step hydrogen plasma treatment step.
Step 606: fill metal in described via openings, form through hole.
In the present embodiment, the metal of filling in this via openings can be copper metal, tungsten metal or aluminum metal etc.It both can utilize the method for physical vapour deposition (PVD) to form, and also can utilize electric plating method to form.
In other embodiments of the invention, can also utilize the formation method of conductive structure of the present invention to form other conductive structures such as contact hole or dual-damascene structure, particularly, can utilize the method for the etching stop layer in above-mentioned removal through-hole structure to remove the etching stop layer in contact hole or dual-damascene structure, can reach equally the formation quality that improves contact hole or dual-damascene structure, improve the object of device electrical performance.Its concrete implementation step is all similar with the present embodiment to thinking, and under the enlightenment of first embodiment of the invention, the extension of this application is easy to understand and realization for those of ordinary skills, does not repeat them here.
The second embodiment:
Figure 10 is the flow chart of the bonding pad forming method of explanation second embodiment of the invention, Figure 11 to Figure 16 is the device profile schematic diagram of the bonding pad forming method of explanation second embodiment of the invention, below in conjunction with Figure 10 to Figure 16, the second embodiment of the present invention is elaborated.
Step 1001: the substrate that forms lower floor's conductive structure is provided;
The copper metal connection structure that in the present embodiment, in substrate, established copper conductive structure is top layer, it can be connected with the copper metal connection structure of lower floor, also can be connected with the conductive structure of the metal oxide semiconductor transistor of lower floor.
The generalized section of the substrate providing in the bonding pad forming method that Figure 11 is second embodiment of the invention, as shown in figure 11, in substrate 1101, form conductive structure 1102, in the present embodiment, the top-level metallic connecting line construction of conductive structure 1102 in substrate 1101 for being connected with the copper metal connection structure of lower floor, it can be formed by copper metal.
Step 1002: form etching stop layer on described substrate.
Because the etch rate between the different region of device closeness and between central area and fringe region has bigger difference; Or because of etching remove each layer deposit time there is consistent situation in uneven thickness, all can cause the etching result of zones of different on same substrate inconsistent.For fear of the problems referred to above, while guaranteeing below etching passivation layer, can obtain the comparatively etching result of uniformity, can before deposit passivation layer, first on substrate, form one deck etching stop layer.
Figure 12 forms the device profile schematic diagram after etching stop layer in the bonding pad forming method of second embodiment of the invention, as shown in figure 12, on substrate, form etching stop layer 1103, the material that the material require that this etching stop layer 1103 is selected is selected from passivation layer is different, and etch rate wants much slow.
In the present embodiment, passivation layer has been selected silica material, and etching stop layer 1103 can be selected the materials such as silicon nitride, silicon oxynitride or carborundum.Specifically in the present embodiment, select silicon nitride material, it has lower etch rate under the etching condition of silica, can guarantee the etching energy of passivation layer comparatively to stop in etching stop layer 1103 uniformity, prevents that the conductive structure 1102 of lower floor from sustaining damage.
Under normal circumstances, the thickness of etching stop layer 1103 can be arranged on 300
to 600
between.The setting of the thickness of concrete etching stop layer is poor with the etch rate of itself and passivation layer, the etching depth of passivation layer etc. is relevant.When the etching depth of the poor large or passivation layer of the two etch rate hour, can the thickness of etching stop layer be arranged littlely, otherwise need to arrange greatlyr.
Step 1003: form passivation layer on described etching stop layer.
Figure 13 forms the device profile schematic diagram after passivation layer in the bonding pad forming method of second embodiment of the invention, as shown in figure 13, has formed passivation layer 1105 on etching stop layer 1103.The effect of this passivation layer is that the non-electric-connecting region on substrate forms insulating medium layer, to protect non-electric-connecting region, and each pad is kept apart.This passivation layer 1105 can be formed by silica or silicon oxy-nitride material conventionally, and its thickness conventionally at least need to be
above, as
deng.
Step 1004: form bonding pad opening figure on described passivation layer.
On passivation layer 1105, cover photoresist, recycling photoetching process forms bonding pad opening figure.
Step 1005: described in etching, passivation layer forms bonding pad opening.
Figure 14 forms the device profile schematic diagram after bonding pad opening in the bonding pad forming method of second embodiment of the invention, and as shown in figure 14, the bonding pad opening figure that utilizes photoresist to form is mask, and etching passivation layer 1105, forms bonding pad opening 1108 therein.After this step etching completes, still can residual fraction photoresist 1106 on substrate, and on the sidewall of bonding pad opening 1108, can adhere to some polymer 1110.
Then, can remove the operation of the polymer 1110 producing in residual photoresist 1106 and this step etching.This operation can utilize microwave to carry out under higher temperature conventionally, also can utilize special ashing resist remover to carry out.
Removing after residual photoresist 1106, can also add a step wet clean step, to remove photoresist residue and residual polymer.This cleaning operation can utilize SC1 cleaning fluid to complete.
Step 1006: the etching stop layer of bonding pad opening bottom described in etching, and the oxygen flow adding in described etching process is between 15 to 25sccm.
This step etching can utilize inductively coupled plasma etching machine (Inductive CoupledPlasma, ICP) to complete.
In the present embodiment, in order to overcome the defect being prone in pad in prior art, etching mechanism is conducted in-depth analysis.Use oxygen to replace traditional hydrogen as etching gas, and the flow of oxygen has been carried out to strict control.
In prior art, the flow that passes into oxygen in etching conventionally can be less or larger, and as passed into sometimes a small amount of oxygen when the materials such as etch silicon nitride, its conventional flow is also only in 10sccm left and right, even less, to obtain larger etch rate.But experiment is found, in the time removing etching stop layer 1103, if flow of oxygen is less, the etch-rate of etching stop layer 1103 (being silicon nitride material in the present embodiment) can be crossed faster than passivation layer 1105 (being silica material in the present embodiment), therefore, if adopt the conventional amount used of existing etch silicon nitride, can form the depression 510 shown in Fig. 5.
In addition, in prior art, in the time that removing photoresist, etching conventionally can select larger oxygen flow, as more than hundreds of sccm.But find in practical operation, if flow of oxygen is too many, the etch-rate of silicon nitride can be less than silica, now, removed by complete etching in order to ensure the silicon nitride material as etching stop layer 1103, having the passivation layer 1105 more being formed by silica material is removed and (notices now and there is no photoresist protection on passivation layer 1105, it can lose more), and the thickness of passivation layer 1105 has requirement, can not be excessively thin, this can only arrange less over etching rate (ratio between over etching time and main etching time) while just making etching remove etching stop layer 1103, result be easy to cause having part bonding pad opening not etching put in place, make the resistance value of bonding pad opening larger, device electrical performance is poor.
In the present embodiment, oxygen flow is strictly limited between 15 to 25sccm, can obtain the etching selection ratio between comparatively suitable passivation layer 1105 and etching stop layer 1103 on the one hand, on the other hand can also because of introduce oxygen realize in etching process to polymer number adjustment, thereby guaranteed to obtain more preferably bonding pad opening from above-mentioned two aspects.
In addition, can also utilize oxygen in etching, to remove partial polymer, making only has a small amount of polymer deposition in open bottom in etching process or does not substantially have, thereby obtains more clean bonding pad opening.Utilize the bonding pad forming method in the present embodiment, can improve the formation quality of pad, effectively improve the electrical property of device.
The condition of work of this step etching after optimization can be set to: substrate to be etched is put into plasma etching equipment, vacuumize, pass into etching gas and assist gas, at room temperature (be generally 25 DEG C of left and right) and carry out plasma etching treatment.Wherein, chamber pressure can be arranged between 5 to 20mTorr, as is 5mTorr, 10mTorr, 15mTorr or 20mTorr etc.; Etching power adjustments to 200 is between 600W, as is 200W, 300W, 400W or 600W etc.
The oxygen flow passing in etching process is strict controlled between 15 to 25sccm, as is 15sccm, 18sccm, 22sccm or 25sccm etc.The etching gas of the carbon containing fluorine simultaneously passing into, as CF
4, CF
8, C
5f
8, C
4f
6, CHF
3between 30 to 80sccm, as be 30sccm, 40sccm, 50sccm, 60sccm, 70sccm or 80sccm etc. Deng, flow set.
In the present embodiment, this stage has also added assist gas, and as argon gas, its flow can be between 150 to 250sccm, as are 150sccm, 180sccm, 200sccm or 250sccm etc.This assist gas can regulate the concentration of etching gas in chamber on the one hand, and then changes etch rate; The pressure that also can be used for adjusting on the other hand chamber, makes it remain on set point.
Figure 15 removes the device profile schematic diagram after etching stop layer in the bonding pad forming method of second embodiment of the invention, as shown in figure 15, remove after etching stop layer 1103, residual photoresist 1106 is removed originally, and the etching stop layer 1103 of bonding pad opening 1108 bottoms is removed.
Remove after etching stop layer 1103 in etching, in the present embodiment, also add the hydrogen plasma treatment step of a step original position, deoxidation processing is carried out on surface with the lower floor's conductive structure to may be partially oxidized in etching process, further improves the formation quality of pad.
In the present embodiment, this step is as follows with the process conditions of the in-situ hydrogen plasma treatment step that removal etching stop layer 1103 completes in same etching apparatus: maintain the temperature-resistant of chamber, chamber pressure still can be arranged between 5 to 20mTorr, etching power also can with keep on last stage identical, as can be still remained between 200 to 600W, as be 200W, 300W, 400W or 600W etc.The etching gas that stops passing on last stage and assist gas, change into and only pass into hydrogen, and its flow can be arranged between 300 to 800sccm, as be 300sccm, 500sccm, 600sccm or 800sccm etc.
In the present embodiment, in the time that etching is removed etching stop layer, can also add certain bias voltage (bias power), to make the bombardment of the plasma in chamber there is certain directivity, improve the efficiency (this bias voltage can be arranged between 100 to 200W conventionally) of removing photoresist or etching stop layer.And in the time carrying out hydrogen plasma processing, bonding pad opening 1108 bottoms have exposed lower floor's conductive structure 1102, and its object is only to utilize hydrogen plasma to carry out deoxidation processing to these lower floor's conductive structure 1102 surfaces.For preventing that hydrogen plasma damage from having exposed lower floor's conductive structure 1102 outside to the open air, in the present embodiment, do not apply bias voltage in this step hydrogen plasma treatment step.
After etching, can also add again a step wet clean step, this step is cleaned and can be adopted the cleaning fluids such as SC1 to carry out, its after upper step can being processed still residual a small amount of polymer clean and remove.In the present embodiment, take hydrogen plasma to process the copper conductive structure surfaces of lower floor has been carried out to deoxidation, guarantee that copper conductive structure 1102 surfaces of exposing to the open air bonding pad opening 1108 bottoms do not form cupric oxide substantially, therefore, this step is cleaned and can not caused causing the shaggy problem of copper conductive structure 1102 because cupric oxide is removed in prior art.
In the present embodiment, for preventing that metallic copper from diffusing in pad, between the conductive structure 1102 of copper and aluminum pad, can first form one deck barrier layer 1107, on described passivation layer and in described bonding pad opening, cover one deck barrier layer according to pattern.
This barrier layer 1107 can adopt Ta, W, and Ti and their nitride TiN, WN, the materials such as TaN form.After the hydrogen plasma of the present embodiment is processed, be positioned at conductive structure 1102 smooth surfaces under barrier layer 1107, the covering quality on barrier layer 1107 is improved, and can stop better copper metal to diffuse in pad.
Step 1007: covering aluminum metal in described bonding pad opening, forms pad.
Figure 16 forms the device profile schematic diagram after pad in the bonding pad forming method of second embodiment of the invention, as shown in figure 16, utilize physical vapour deposition (PVD) (PVD, Physical VaporDeposition) method, as the method for sputtered aluminum target, covering aluminum metal on the substrate forming behind barrier layer 1107.Then, utilize the method for photoetching to form land pattern thereon; Then, utilize lithographic method to form pad 1111 taking the land pattern of photoresist as mask etching.Through the above-mentioned processing of the present embodiment, the pad quality forming is significantly improved, and not only sidewall shape is good,
Do not occur again that copper metal diffuses to the phenomenon in aluminum pad yet.
Figure 17 is the bonding pad opening profile that utilizes second embodiment of the invention method to form, and it is 20sccm removing oxygen flow used when etching stop layer, and chamber pressure is at 10mTorr, etching gas CF
4flow is in 50sccm left and right, and etching power is 40W.The bonding pad opening that etching forms is with this understanding as shown in circle in Figure 17 1701, and between etching stop layer and passivation layer, sidewall has kept level and smooth shape substantially, and the bonding pad opening sidewall shape forming is good, has improved the formation quality of pad.
Although the present invention with preferred embodiment openly as above; but it is not for limiting the present invention; any those skilled in the art without departing from the spirit and scope of the present invention; can make possible variation and amendment, therefore protection scope of the present invention should be as the criterion with the scope that the claims in the present invention were defined.
Claims (13)
1. a formation method for conductive structure, is characterized in that, comprises step:
The substrate that forms lower floor's conductive structure is provided;
On described substrate, form successively etching stop layer and interlayer dielectric layer;
On described interlayer dielectric layer, define conductive structure opening figure;
Taking described conductive structure opening figure as mask, interlayer dielectric layer forms conductive structure opening described in etching, and conductive structure opening sidewalls is attached with polymer;
Remove the polymer that described conductive structure opening sidewalls adheres to;
The etching stop layer of conductive structure open bottom described in etching, and the oxygen flow adding in described etching process is between 15sccm to 25sccm, so that the sidewall shape of conductive structure opening is good; In the stop-layer of conductive structure open bottom described in oxygen etching, remove the described polymer of part;
In described conductive structure opening, fill metal, form conductive structure.
2. formation method as claimed in claim 1, is characterized in that: the flow of the carbon containing fluorine gas adding in described etching process is between 30sccm to 80sccm.
3. formation method as claimed in claim 1 or 2, is characterized in that: in described etching process, also added inert gas.
4. formation method as claimed in claim 3, is characterized in that: the flow of described inert gas is between 150sccm to 250sccm.
5. formation method as claimed in claim 1, is characterized in that: after etching is removed described etching stop layer, also carried out in-situ hydrogen plasma treatment.
6. formation method as claimed in claim 5, is characterized in that: when described in-situ hydrogen plasma treatment, pass into the flow of hydrogen between 300sccm to 800sccm.
7. formation method as claimed in claim 5, is characterized in that: the chamber pressure in described etching and in-situ hydrogen plasma treatment procedure is between 5mTorr to 20mTorr.
8. formation method as claimed in claim 1, is characterized in that: described conductive structure comprises any in contact hole, through hole or dual-damascene structure.
9. a formation method for pad, is characterized in that, comprises step:
The substrate that forms lower floor's conductive structure is provided;
On described substrate, form etching stop layer;
On described etching stop layer, form passivation layer;
On described passivation layer, define bonding pad opening figure;
Taking described bonding pad opening figure as mask, passivation layer forms bonding pad opening described in etching, and bonding pad opening sidewall is attached with polymer;
Remove the polymer that described bonding pad opening sidewall adheres to;
The etching stop layer of bonding pad opening bottom described in etching, and the oxygen flow adding in described etching process is between 15sccm to 25sccm, so that the sidewall shape of conductive structure opening is good; In the stop-layer of bonding pad opening bottom described in oxygen etching, remove the described polymer of part;
Covering aluminum metal in described bonding pad opening, forms pad.
10. formation method as claimed in claim 9, is characterized in that: the flow of the carbon containing fluorine gas adding in described etching process is between 30sccm to 80sccm.
11. formation methods as claimed in claim 9, is characterized in that: after etching is removed described etching stop layer, also described substrate has been carried out to in-situ hydrogen plasma treatment.
12. formation methods as claimed in claim 11, is characterized in that: when described in-situ hydrogen plasma treatment, pass into the flow of hydrogen between 300sccm to 800sccm.
13. formation methods as claimed in claim 11, is characterized in that: the chamber pressure in described etching and in-situ hydrogen plasma treatment procedure is between 5mTorr to 20mTorr.
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| CN103531534B (en) * | 2013-03-15 | 2016-02-03 | 上海华力微电子有限公司 | The lithographic method of metal valley |
| CN105161434A (en) * | 2015-06-29 | 2015-12-16 | 上海华虹宏力半导体制造有限公司 | PAD etching technological method |
| CN105513949B (en) * | 2015-12-30 | 2019-03-12 | 上海华虹宏力半导体制造有限公司 | The method for forming carbon substrate articulamentum |
| CN107123596A (en) * | 2017-05-19 | 2017-09-01 | 武汉新芯集成电路制造有限公司 | A kind of dry etching method |
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