Background technology
In fabrication of semiconductor device, often need on wafer, define the pattern of superfine micro-dimension, the definition of these patterns mainly is to finish by lithographic technique.So-called lithographic technique is exactly with the technology that the wafer surface material is evenly removed or the pattern selectivity is partly removed, and can be divided into two kinds of wet etching and dry etchings.Wherein, wet etching is to remove the wafer surface material with liquid chemical reagent with chemical mode, because of it has isotropism, generally only is used for larger-size situation.
Dry etching then is that wafer surface is exposed in the plasma that produces in the gaseous state, by plasma and wafer generation physics and chemical reaction, removes the surfacing that exposes to the open air.Dry etching generally has stronger directivity, can obtain higher anisotropic etching section, controls live width preferably, is the topmost method of etched features under the submicron-scale.At present, dry etching has become one of critical process in the integrated circuit manufacturing, and this technological level will directly have influence on the advance of end product quality and production technology.
Along with very lagre scale integrated circuit (VLSIC) device feature size scaled down constantly, integrated level constantly improves, and is also more and more higher to the requirement of the lithographic technique that can intactly mask pattern be copied to wafer surface.Not only require the fidelity of figure transfer to want high, the selection of etching is than high, and the uniformity of etching will be got well; Also require etching apparatus in scale of mass production, can guarantee high stability, extremely low ratio of defects simultaneously.
Figure 1A is the existing generalized section of device being carried out dry etching of explanation to 1C.Figure 1A is the device profile schematic diagram before the etching, shown in Figure 1A, somatomedin layer 102 on silicon substrate 101, and in the wafer surface coating photoresist 103, form figure.Figure 1B is the device profile schematic diagram after the etching, shown in Figure 1B, removes by the dielectric layer 102 that etching will not protected by photoresist; realization is with on the dielectric layer of figure transfer below photoresist; in the etching process, use the plasma that etching reaction gas produced usually and carry out etching, as CF
4, CF
8, C
5F
8, C
4F
6, CHF3, BCl3 etc., meetings such as they and photoresist, etching product produce certain combining, and form polymer 104, this polymer can stop the etching of oppose side wall, strengthens the directivity of etching, thereby realizes the good control to graphics critical dimension.The generation of etch polymers has multiple reason, and composition is also quite complicated, and the influence that it is subjected to comprising the multiple material of etching gas, etching material, protective layer, etching stop layer and subsurface material has the very strong carbon-fluorine bond that is difficult to oxidation and removal.But these polymer must be removed after etching is finished, otherwise will become particle and the contamination sources that increases wafer surface blemish density, damage device function, influence the rate of finished products and the reliability of device.Therefore, the removal of these polymer has become etching technics must process after finishing a committed step, the quality of its removal effect also receives much concern.Fig. 1 C is the device profile schematic diagram that residual polyalcohol after etching fails to remove fully in the prior art, shown in Fig. 1 C, after etching is finished, if fail to remove fully polymer, then still can more residual polymer particles 105 in the groove of etching, these residual polyalcohol particulates are generally all very little, even can escape from the technological process that normal microscopy enters the back, but carrying out along with technology, these residual polymer particles tend to be moved, form particle defects in wafer surface, and finally device performance is caused irremediable influence.
The existing method of removing residual polyalcohol after etching mainly contains two kinds, and a kind of is the method for utilizing chemical corrosion to clean, and is another kind of then be the method for utilizing over etching, but two kinds of methods all have the place of deficiency.For the former, be after etching, to adopt special chemical gas or strong solvent that wafer is cleaned to remove residual polymer, as cleaning, use O with EKC or SCl liquid
2Handle etc.But in the reality, these measures often can not be removed residual polyalcohol totally fully, polymer particles that still can residual lower part indissoluble.For the latter, be after etching is finished, adopt the etching gas different again wafer to be carried out the plasma over etching and handle, to eliminate the polymer in the etching groove with main etching.But this side is difficult to realize accurate control, in case excessive over etching occurs, then can deepen the damage to wafer on the one hand, on the other hand, also can have influence on the section shape of pattern, and then have influence on the control to live width.So, in fact be difficult to realize by over etching merely the removal fully of residual polyalcohol after etching.
Application number is the composition that 03816222.9 Chinese patent discloses a kind of selective clearing etch residue, said composition includes deionized water, organic dicarboxylic acid, organic or inorganic alkali, fluoride ion compound and anticorrosive etc., can remove residual polymer after the etching.But nearly more than eight kinds, cost is higher for the composition kind in this method; And the composition proportioning is also comparatively complicated, especially requires the final ph value of said composition is carried out strict control, and this has certain degree of difficulty in operation, be difficult for realizing.
Summary of the invention
The invention provides a kind of method, semi-conductor device manufacturing method of removing residual polyalcohol after etching, this method utilizes the heat treatment after the etching to realize removal to residual polyalcohol.
A kind of method, semi-conductor device manufacturing method of removing residual polyalcohol after etching provided by the invention comprises step:
On substrate, form layer of material layer at least;
Described material layer is carried out etching;
Substrate is heat-treated.
Wherein, described material layer is a kind of or its combination in silica, silicon nitride, silicon oxynitride, tantalum oxide, barium strontium, polysilicon, monocrystalline silicon and the metal.
Wherein, described etching is a plasma etching.
Wherein, described heat treatment is quick thermal annealing process or high temperature furnace annealing in process, has fed a kind of in the mist of nitrogen, argon gas or nitrogen and oxygen in the heat treatment process; Heat treated temperature is 300 ℃-1350 ℃, and heat treatment period is between 3 seconds to 60 minutes.
Wherein, described method further comprises utilizes mask that material layer is carried out graphical treatment, and to the removal and the cleaning process of described mask.
The present invention has the method for the another kind removal residual polyalcohol after etching of identical or relevant art feature, is that the substrate after the etching is heat-treated.
Wherein, described heat treatment is quick thermal annealing process or high temperature furnace annealing in process, feeds a kind of in the mist of nitrogen, argon gas or nitrogen and oxygen in heat treatment process; Heat treated temperature is 300 ℃-1350 ℃, and heat treatment period is between 3 seconds to 60 minutes.
Compared with prior art, the present invention has the following advantages:
Adopt the method, semi-conductor device manufacturing method of removing residual polyalcohol after etching provided by the invention,, make residual difficult dissolving polymer be removed by high-temperature process by after etching, wafer being heat-treated.In actual process, by process sequence is adjusted, after all finishing, the etching that thermal anneal process in the device manufacturing process is moved to multilayer material carries out again, just processing step can not increased, do not increase the process time, do not increase the removal that realizes residual polyalcohol of the present invention under the situation of technology difficulty yet, improve the rate of finished products of product.Simultaneously, the present invention can also reduce the step and the time of cleaning effectively, has reduced production cost, has improved production efficiency.
Embodiment
For above-mentioned purpose of the present invention, feature and advantage can be become apparent more, the specific embodiment of the present invention is described in detail below in conjunction with accompanying drawing.
The present invention can remove the method, semi-conductor device manufacturing method of residual polyalcohol after etching, utilizes the heat treatment of after etching wafer being carried out that residual difficult dissolving polymer is carried out pyrolysis, and residual difficult dissolving polymer is removed.
Often need the material of more than one deck is carried out the multistep etching in the actual technology manufacture process, remove residual polymer if all heat-treat after each etching, can cause the production cycle lengthening, reality also there is no need.Can after all finishing, the multistep etching that needs carry out heat-treat the removal once of the polymer that stays after the realization multiple etching again.In addition, itself also need in the technology manufacture process wafer is carried out some high-temperature heat treatment,, just need carry out rapid thermal annealing or high temperature furnace annealing in process,, further improve the electric property of device to activate the impurity that injects to wafer as after doping.Thereby as long as process sequence is carried out some adjustment, this high temperature processing step is moved to carry out again after the multistep etching is finished, just can realize the present invention easily, need not to add extra processing step, to production cycle and also not influence of production cost.
The first embodiment of the present invention is an example with the silicon oxide layer on the etching silicon chip, and the device manufacturing processes of heat-treating behind the etching layer of material to remove residual polyalcohol is described.Fig. 2 can remove the schematic flow sheet of first embodiment of the method, semi-conductor device manufacturing method of residual polyalcohol after etching for the present invention, illustrate that in conjunction with Fig. 2 first embodiment is as follows:
At first, at wafer deposition layer of silicon dioxide (S201), then, at its surface coated photoresist, photoetching forms figure (S202).To note the selection of photoresist in this step process, preferably be chosen in the photoresist type of being stripped from easily behind the plasma etching, reduce the removal difficulty of residual photoresist after the etching.In addition, the thickness of photoresist will enough be protected the silicon dioxide of not wishing the silicon chip surface that is etched, concrete thickness generally by the etch rate of the photoresist and the material that is etched than and the etching depth estimated determined.
Then, carry out dry etching litho pattern is transferred to (S203) on the silicon chip.Present embodiment employing reactive ion etching (RIE, Reactive Ion Etch) utilizes etching gas to carry out chemical reaction and the material silicon dioxide that is etched is removed in the physical ion bombardment, and the used gas of etching comprises C
4F
8, its range of flow as is 20sccm between 5 to 30sccm; O
2, its range of flow as is 10sccm between 5 to 15sccm; Ar, its range of flow as are 350sccm between 200 to 500sccm; CO, its range of flow as are 300sccm between 200 to 500sccm.
In the etching, etching reaction gas can combine with photoresist, etching product, produces the complicated polymer that contains carbon (C), fluorine (F), nitrogen (N), oxygen elements such as (O), need remove after etching.
After the etching, need enter cleaning step to remove residual photoresist and polymer (S204) after the etching.After removing photoresist, adopt the SCl basic cleaning solution of heat to remove organic contamination, comprise photoresist residue and the softer residual polyalcohol of part that the back of removing photoresist is remaining.But, only generally can't remove by the cleaning of chemical solution for the harder residual polyalcohol particulate of part.
Clean the residual harder polymer particles of part in back for thoroughly removing, present embodiment has carried out heat treatment (S205) to silicon chip.Silicon chip after cleaning is put into rapid thermal anneler, feed nitrogen (N
2) and oxygen (O
2) mist, its flow-rate ratio as is 2 between 0.5 to 10; After treating steady air current, fast temperature is brought up to 300 ℃ to 1350 ℃, as be 800 ℃; Heat treated setting-up time can be between 3 seconds to 60 minutes, as are 10 seconds.In this heat treatment process, high temperature can make residual polymer shrink the N of feeding
2Can soften polymer particles, O
2Can make polymer combustion, and the most residual harder polymer particles that is difficult to remove decomposes and gets rid of.Figure 3 shows that the device architecture profile after the heat treatment in the present embodiment, as shown in Figure 3, originally in wafer surface and groove after the residual etching polymer be removed.
That feed in the heat treatment process of present embodiment is nitrogen (N
2) and oxygen (O
2) mist, in other embodiments of the invention, can also feed argon gas (Ar), hydrogen (H
2) wait other gas.
The heat treatment utilization of present embodiment be rapid thermal anneler, also can utilize high temperature furnace to carry out in other embodiments of the invention, or adopt and in rapid thermal anneler, to heat-treat earlier, the method for heat-treating at high temperature furnace again is with the further device performance that improves.The process conditions of high temperature furnace annealing can for: temperature between 600 ℃ to 1350 ℃, as be 800 ℃, the processing time as was 10 minutes between 3 minutes to 60 minutes.
The second embodiment of the present invention is an example to form dual damascene (dual-damascene) structure, has illustrated respectively and has heat-treated to remove the process of all residual polyalcohols behind the etching multilayer material again.Fig. 4 is the schematic flow sheet of explanation second embodiment of the invention, and Fig. 5 is the device architecture profile in the second embodiment of the invention, in conjunction with Fig. 4 and Fig. 5, illustrates that the second embodiment of the present invention is as follows:
As shown in Figure 4, at first deposit first second and third dielectric layer is coated with photoresist, finishes the photoetching (S401) of through hole.Fig. 5 A is the device architecture profile after this step is finished, and shown in Fig. 5 A, what first dielectric layer 502 of deposit adopted on silicon chip 501 in the present embodiment is boron-phosphorosilicate glass, and its thickness as is 200nm between 100 to 500nm; Second dielectric layer 503 of deposit has adopted the tetraethyl silica on first dielectric layer 502, and thickness as is 500nm between 300 to 800nm; Then will be on second dielectric layer 503 deposit one deck polysilicon as hard mask (the 3rd dielectric layer 504); be chosen in the photoresist 505 of being stripped from easily behind the plasma etching again and be coated on wafer surface; the good figure of photoetching, next step will carry out etching 506 to the material of not protected by photoresist.
Then, first and second and the 3rd dielectric layer of not protected by photoresist carried out whole etching and form through hole (S402).The used gas of this step etching technics comprises C
4F
8, its range of flow as is 20sccm between 5 to 30sccm; O
2, its range of flow as is 10sccm between 5 to 15sccm; Ar, its range of flow as are 350sccm between 200 to 500sccm; CO, its range of flow as are 300sccm between 200 to 500sccm.
Behind the etching through hole, the cleaning (S403) of removing photoresist.After removing residual photoresist, adopt the SCl basic cleaning solution of heat to remove organic contamination again, comprise photoresist residue and the softer residual polyalcohol of part that the back of removing photoresist is remaining, through cleaning the polymer particles that sidewall on residual fraction is harder.Fig. 5 B is the device architecture profile after through hole forms, and shown in Fig. 5 B, by being clear that among the figure, after the cleaning, still is attached with the polymer particles 508 that partial etching produces on the sidewall of the through hole 507 that etching forms.
Then, carry out ion and inject (implant) (S404).Silicon materials to the via bottoms that exposes to the open air carry out doping treatment, to improve the electrical property of metal contact layer.But after simple ion injected, the lattice of silicon chip can sustain damage because of atom is clashed into lattice structure, and simultaneously, the ion of injection also can rest on the position of interstitial void, can not play the effect that improves electric property.So, in traditional handicraft, need after ion injects that it is carried out high-temperature thermal annealing and handle, repair lattice defect and make impurity move to lattice-site, activator impurity.In the present embodiment, to move after the high-temperature thermal annealing processing of after ion injects, carrying out originally, after finishing, the operation that second dielectric layer 503 and the 3rd dielectric layer 504 etchings is formed groove carries out again, to realize the thorough removal of polymer residual after all layers etching simultaneously.
Follow again, make groove (S405).On the 3rd dielectric layer, be coated with photoresist, finish the photoetching of groove, and the second and the 3rd dielectric layer is carried out etching, form groove 509.Wherein, the gas of etching employing comprises C
5F
8, its range of flow as is 10sccm between 5 to 20sccm; O
2, its range of flow as is 10sccm between 5 to 15sccm; Ar, its range of flow as are 350sccm between 200 to 500sccm; CO, its range of flow as are 300sccm between 200 to 500sccm.
After etching is finished, the cleaning (S406) of removing photoresist once more.Be equally after removing photoresist, adopt the SCl basic cleaning solution of heat to clean.Fig. 5 C is the device architecture profile after cleaning, and shown in Fig. 5 C, the polymer particles 508 that still residual partial etching produces on the sidewall of the groove 509 that etching forms fails to remove.
Then, again wafer is carried out thermal anneal process (S407).Silicon chip is put into quick anneal oven, carry out the original rapid thermal anneal process of after ion injects, finishing, repair lattice defect and make impurity move to lattice-site, activator impurity on the one hand; On the other hand can with behind the twice etching in through hole and groove the residual polymer that does not wash remove.Before the annealing, feed nitrogen (N
2) or argon gas (Ar), its flow as is 150sccm between 50 to 300sccm; After treating steady air current, fast temperature is brought up between 600 ℃ to 1350 ℃, as be 1000 ℃; Heat treatment period can be more than 3 seconds, as are 10 seconds; And then cooling rapidly, finish quick thermal annealing process.In this heat treatment process, high temperature can make residual polymer shrink, even disappears.
The thermal anneal process process also can utilize high temperature furnace to carry out, or quick thermal annealing process and high temperature furnace annealing in process combined carries out, with the further device electrical performance that improves.The process conditions of high temperature furnace annealing are: temperature as is 800 ℃ between 600 ℃ to 1350 ℃, and the processing time as was 10 minutes between 3 minutes to 60 minutes.
Fig. 5 D is the device architecture profile after the heat treatment, and shown in Fig. 5 D, at this moment, residual polymer is removed.
In addition, in thermal annealing process, to monitor, note the cleaning in the maintenance stove, to prevent in annealing process, introducing new defective the particle situation in the annealing furnace.
At last, depositing metal with unnecessary metal removal, forms metal connecting line (S408) by CMP.Fig. 5 E is the device architecture profile after metal connecting line forms, and shown in Fig. 5 E, is filled with tungsten (W) 510 in through hole 507 and groove 509.
Fig. 6 is for adopting the inventive method front and back polymeric detection comparison diagram as a result.As shown in Figure 6,601 expressions to be thermal anneal process forming the testing result of carrying out before the groove, the testing result that to be thermal anneal process carry out after forming groove again of 602 expressions, by can obviously seeing among the figure, after adopting the present invention can remove the method, semi-conductor device manufacturing method of residual polyalcohol after etching, the polymer of silicon chip surface has tangible minimizing.
Fig. 7 can remove the method, semi-conductor device manufacturing method front and back device yield comparison diagram of residual polyalcohol after etching for adopting the present invention.As shown in Figure 7,701 expressions be not adopt heat treatment to remove the rate of finished products result of the device of etching residual polyalcohol, 702 expressions be to adopt heat treatment to remove the rate of finished products result of the device of etching residual polyalcohol, by seeing among the figure, after adopting the present invention can remove the method, semi-conductor device manufacturing method of residual polyalcohol after etching, the rate of finished products of device is significantly improved.
In the dual damascene formula technology of present embodiment, formed through hole earlier, form groove again, in other embodiments of the invention, also can adopt first etching second dielectric layer to form groove, etching first dielectric layer forms the dual damascene formula process of through hole again, and this method equally also can be after secondarily etched work be all finished, carry out thermal anneal process again, realize the dual purpose that impurity activation and polymer are removed.
In the present embodiment, what first, second and the 3rd dielectric layer adopted respectively is boron-phosphorosilicate glass, tetraethyl silica and polysilicon layer, in other embodiments of the invention, can also adopt other dielectric layers such as silicon nitride, carborundum, silicon oxynitride.
More than each embodiment the residual polyalcohol after etching in the silicon chip manufacturing process is removed, can adopt higher heat-treat condition, in other embodiments of the invention, also can wait material on the substrate of other material to heat-treat to remove residual polymer after its etching to GaAs (GaAs), gallium nitride (GaN), may need this moment with lower temperature, as about 300 ℃ to 600 ℃, equally also can realize the removal of residual polyalcohol.
The foregoing description is to heat-treat together behind three layers of dielectric layer of etching, can also be in other embodiments of the invention after respectively more multi-layered material being carried out etching, to heat-treat, once thoroughly to remove residual all polymer after the multistep etching again.Wherein etch material can be dielectric layer, semiconductor layer or metal level, as silica, silicon nitride, silicon oxynitride, tantalum oxide (Ta
2O
5), barium strontium (BST), polysilicon, monocrystalline silicon, aluminium, copper, tungsten etc.But notice that for metal material its fusing point is depended in the selection of its annealing temperature, that is, heat treated temperature must be lower than the fusing point of metal.
Though the present invention with preferred embodiment openly as above; but it is not to be used 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 change and modification, so protection scope of the present invention should be as the criterion with the scope that claim of the present invention was defined.