JP4968028B2 - Resist remover - Google Patents

Description

  The present invention relates to a technique for removing a resist formed on a surface of a substrate in a manufacturing process of a semiconductor element, particularly a high dose ion implantation resist.

  As a technique for removing the high dose ion implantation resist on the substrate, for example, there is one disclosed in the following patent document.

  The plasma processing method and apparatus of Patent Document 1 perform plasma processing on a substrate using helicon wave plasma processing having substrate bias applying means and substrate heating means. Specifically, the resist mask on the substrate is removed by ion mode-based plasma processing using a high ion current by helicon wave plasma and radical mode-based plasma processing by non-resonant inductively coupled plasma.

  In the plasma processing method and apparatus of Patent Document 2, the hardened altered layer of the resist mask of the substrate is ashed by a plasma processing apparatus having a helicon wave plasma generation source having a transparent bell jar made of a dielectric material transparent to UV light. Next, the unaltered layer of the resist mask on the substrate is ashed by UV light irradiation in ozone.

The resist removal method and apparatus of Patent Document 3 intentionally cause a popping phenomenon in the resist on the substrate surface by heating the substrate. And after cooling this board | substrate, the said resist is peeled off with an adhesive tape, and ashing is performed by oxygen plasma, ozone (for example, refer patent document 4 etc.) or the combination of UV and ozone continuously.
JP-A-8-69896 (paragraphs 0010 to 0016) JP-A-8-139004 (paragraphs 0011 to 0023) JP-A-9-27473 (paragraphs 0008 to 0011) JP 2006-294842 A (paragraphs 0016, 0026)

  In the high dose ion implantation resist, a hardened layer is formed in a film shape on the surface of the substrate. Since there is a soft resist (unmodified layer) under the resist, when the substrate is heated, for example, when heated to 200 ° C. or more, the surface is cracked and blown away due to degassing or thermal expansion difference from the underlying unmodified layer. Causes a popping phenomenon. The hardened layer on the blown substrate surface contaminates not only the substrate but also the chamber in which the substrate is stored.

  Therefore, the removal method having the heating step exemplified in Patent Document 3 reduces the yield of devices obtained from the substrate. In addition, the maintenance cycle of the manufacturing apparatus must be shortened, which affects the throughput of the substrate.

  On the other hand, the processing methods exemplified in Patent Document 1, Patent Document 2 and Patent Document 4 can suppress the popping phenomenon, but need to have a plasma generator. The plasma generation apparatus is expensive, and if it is provided, the apparatus configuration for removing the resist becomes large. In addition, the energy cost for removing the resist increases.

  The resist removal method using ozone and unsaturated hydrocarbon gas can be processed at low temperature and the equipment configuration is simple, but the conventional method introduces unsaturated hydrocarbon gas from the side wall of the chamber and supplies a high concentration supplied from the top of the sample. Since the resist is removed in a mixed portion with ozone, in a recent large-diameter semiconductor substrate or FPD (Flat Panel Display), an unsaturated hydrocarbon gas having a sufficient concentration cannot reach the central portion of the substrate. As a result, the resist removal rate is lowered and the in-plane uniformity is deteriorated.

Therefore, the problems resist removing apparatus for solving comprises a chamber internal pressure so that the temperature of the substrate is 90 ° C. or less is controlled to lower pressure than the atmospheric pressure stores the substrate heatable, this chamber A shower head that supplies ozone gas and unsaturated hydrocarbon gas to the substrate in an atmosphere in which plasma is not generated, and removes the resist on the substrate, and the shower head circulates the ozone gas. A chamber, an unsaturated hydrocarbon gas chamber through which the unsaturated hydrocarbon gas is circulated, and ozone gas in the ozone gas chamber and unsaturated hydrocarbon gas in the unsaturated hydrocarbon gas chamber are individually diffused on the surface of the substrate. A diffuser member.

According to the above resist removing apparatus , the resist can be removed from the substrate at 90 ° C. or lower, so that the popping phenomenon can be prevented even in the processing of the high dose ion implantation resist. In addition, since the resist on the substrate is removed under a reduced pressure lower than the atmospheric pressure, safety is ensured even if high-concentration ozone gas with a risk of explosion is used. Furthermore, since ozone gas and unsaturated hydrocarbon gas are not separately mixed and provided separately to the substrate, many of the short-lived radical species that contribute to resist removal are efficiently generated near the resist surface. The removal rate and its in-plane uniformity are improved. Examples of the unsaturated hydrocarbon gas include hydrocarbons having a carbon double bond exemplified by ethylene (alkene) and hydrocarbons having a carbon triple bond exemplified by acetylene (alkyne), as well as butylene. It is conceivable to use a low molecular weight.

In the shower head , the ozone gas chamber and the unsaturated hydrocarbon gas chamber may be arranged hierarchically. The apparatus configuration can be reduced in size.

In the shower head , the diffuser member may be formed with a plurality of holes through which the ozone gas is discharged and holes through which the unsaturated hydrocarbon gas is discharged. The resist on the substrate can be removed uniformly.

In the shower head , the hole from which the ozone gas is discharged and the hole from which the unsaturated hydrocarbon gas is discharged may be arranged at equal intervals. In the vicinity of the resist surface of the substrate, the ozone gas and the unsaturated hydrocarbon gas come into contact with each other and react easily, and by this reaction, radical species contributing to resist removal are easily generated uniformly on the resist surface.

In the shower head , the ozone gas chamber is disposed above or below the unsaturated hydrocarbon gas chamber, the ozone gas chamber and the unsaturated hydrocarbon gas chamber are partitioned by a partition plate, and the ozone gas is included in the partition plate. Alternatively, a pipe to which unsaturated hydrocarbon gas is supplied is connected, and the lower end of this pipe may be connected to a hole through which the ozone gas or unsaturated hydrocarbon gas of the air diffuser is discharged. The shower head is further simplified in device configuration and can be downsized.

  Therefore, according to the above invention, the resist removal under a low temperature of 90 ° C. or less can be realized in a uniform manner on the substrate and efficiently performed. Further, since the resist can be removed at the low temperature, the underlying metals are not oxidized. In particular, the high dose ion implantation resist can be removed while preventing the occurrence of the popping phenomenon. Furthermore, since no plasma or the like is used, the energy cost for removing the resist can be reduced and the apparatus configuration can be simplified.

  FIG. 1 is a sectional view showing a schematic configuration of a resist removing apparatus according to an embodiment of the invention.

The resist removal apparatus 1 includes a chamber 2, a vacuum pump 3, and a heater 4. The chamber 2 stores a substrate 16 to be used for removing the resist 17 and introduces ozone gas (O ₃ ) and unsaturated hydrocarbon gas. Examples of the resist 17 include the ArF resist, the KrF resist, the G and I line resists exemplified in FIG.

  The chamber 2 introduces unsaturated hydrocarbon gas and ozone gas from the ceiling. The gas introduced into the chamber 2 is sucked and discharged by the vacuum pump 3 from the bottom.

  Examples of the unsaturated hydrocarbon gas include hydrocarbons having a carbon double bond (alkene) exemplified by ethylene and hydrocarbons (alkyne) having a triple bond exemplified by acetylene. The unsaturated hydrocarbon gas is introduced into the chamber 2 through a pipe 5 connected to the shower head 12 of the chamber 2. A gas cylinder 6 filled with an unsaturated hydrocarbon gas is connected to the pipe 5.

  As the ozone gas, an ultra-high concentration ozone gas is used. The ultra-high concentration ozone gas is introduced through a pipe 7 from an ozone generator 8 exemplified by a pure ozone generator (MPOG-HM1A1) manufactured by Meidensha. The ultra-high concentration ozone gas is obtained, for example, by vaporizing ozone-containing gas again after liquefying and separating only ozone based on the difference in vapor pressure. More specifically, ozone gas obtained from an ozone generator disclosed in Japanese Patent Application Laid-Open Nos. 2001-304756 and 2003-20209 can be given. The ozone generator produces an ultra-high-concentration (ozone concentration≈100%) ozone gas by liquefying and separating only ozone based on the difference in vapor pressure between ozone and other gas components (for example, oxygen). In particular, the ozone supply device disclosed in Japanese Patent Application Laid-Open No. 2003-20209 includes a plurality of chambers that liquefy and vaporize only ozone, and the temperature of these chambers can be individually controlled to continuously supply ultra-high-concentration ozone gas. . The pure ozone generator is exemplified as a commercially available ozone generator based on this ultra-high concentration ozone gas continuous supply system.

  The ozone gas is not limited to the ultra-high concentration ozone gas. For example, ozone gas having an ozone concentration of several tens% or more can be mentioned. This is highly reactive and dangerous under atmospheric pressure, but can be handled safely by using it under reduced pressure. At atmospheric pressure, the ozone concentration ranges from 14.3 to 38 vol% and becomes the persistent decomposition region, the ozone concentration ranges from -44 vol% to the impact region, and the ozone concentration ranges from 44 vol% to the ozone region (Hidetoshi Sugimitsu, Basic and Application of Ozone Kogyosha, 1996, pp. 187).

  The shower head 12 has a function of diffusing unsaturated hydrocarbon gas and ozone gas and a function of a lid for sealing the chamber 2. The shower head 12 seals the chamber 2 via an auxiliary sealing member. As the auxiliary sealing member, for example, an O-ring made of an ozone resistant material such as fluorine rubber or silicon rubber is employed.

The shower head 12 includes a diffuser plate 31, a diffuser tube 32, a frame portion 33, a spacer 34, a partition plate 35, a partition plate frame 36, and a lid 37. The diffuser plate 31 is a member for individually diffusing ozone gas and unsaturated hydrocarbon gas to the substrate 16 in the chamber 2. The diffuser plate 31 is installed so as to close the opening at the top of the chamber 2. The diffuser plate 31 is formed with a plurality of holes 38 for discharging ozone gas and holes 39 for discharging unsaturated hydrocarbon gas. A partition plate frame 36 is installed on the periphery of the upper surface of the diffuser plate 31 via a frame portion 33 . A pipe 5 connected to the gas cylinder 6 is connected to the partition frame 36. Space 41 formed by the partition plate 35 and the partition plate frame 36 serves as a gas chamber in which ozone gas flows. The space 41 is sealed with a lid 37. A pipe 7 is connected to the center of the lid 37. An ozone generator 8 is connected to the pipe 7.

  The holes 38 and 39 are formed so as to be arranged at equal intervals on the surface of the diffuser plate 31 as shown in FIG. The portion where the resist removal speed is fast is more affected by the flow of ozone than the unsaturated hydrocarbon gas, and the portion where ozone is sprayed is faster. Therefore, many kinds of radical species (for example, hydrogen radicals) having a short lifetime that contribute to the removal of the resist 17 by spraying the substrate 16 separately without previously mixing ozone gas and unsaturated hydrocarbon gas as in the diffuser plate 31. Is efficiently generated in the vicinity of the surface of the resist 17 on the substrate 16, and the removal speed is improved. Further, since the holes 38 and 39 are arranged at equal intervals, the ozone species and the unsaturated hydrocarbon gas come into contact with each other and react in the vicinity of the surface of the resist 17 of the substrate 16 to cause the radical species to react with the surface of the resist 17. It tends to occur uniformly on the top.

One end of the diffuser tube 32 is connected to the hole 38. Diffuser tube 32 is a pipe for shifting the ozone gas supplied to the partition plate 35 via a pipe 7 from the ozone generator 8 in the chamber 2. The other end of the air diffuser 32 is fitted into the partition plate 35 . The air diffuser 32 is supported by a spacer 34 . A space 42 formed by the diffuser plate 31, the frame portion 33, the partition plate 35, and the partition plate frame 36 functions as a gas chamber through which the unsaturated hydrocarbon gas supplied from the gas cylinder 6 through the pipe 5 flows . Further, since a sealing member (not shown) is interposed between the spacer 34 and the partition plate 35, the reaction between the unsaturated hydrocarbon and ozone in the space 42 is prevented. The shower head 12 supplies ozone gas from the upper layer and supplies unsaturated hydrocarbon gas from the lower layer, but the gas supply mode according to the invention is not limited to this. Therefore, it is good also as a form which provides an unsaturated hydrocarbon gas from an upper layer, while providing ozone gas from a lower layer.

  The vacuum pump 3 sucks and discharges the gas in the chamber 2 in a reduced pressure state. A plurality of pipes 9 for extracting gas in the chamber 2 are connected to the bottom surface of the chamber 2. The pipe 9 is set to have a larger diameter than the pipes 5 and 7, or the plurality of pipes 9 are arranged uniformly at several locations around the susceptor 4 and below the chamber 2 (opposite to the shower head 12). Even better. The gas flow in the chamber 2 becomes appropriate, that is, the gas flow on the substrate 16 becomes radial, and the in-plane uniformity of the resist removal speed is improved.

  The vacuum pump 3 is connected to one end of the pipe 9. An exhaust valve 10 and an ozone killer 11 are installed on the upstream side of the vacuum pump 3. The opening degree of the exhaust valve 10 can be controlled by the control unit 14. The exhaust valve 10 controls the gas flow in the chamber 2 so that the internal pressure of the chamber 2 becomes a predetermined value. For this purpose, the chamber 2 is provided with a pressure gauge 18 for measuring the internal pressure. The vacuum pump 3 may be a dry pump resistant to ozone. This is in order to avoid a decrease in performance due to ozone gas that may be included in the exhaust gas and a decrease in life due to deterioration. The ozone killer 11 decomposes ozone contained in the gas extracted from the chamber 2. The ozone killer 11 may be a known ozonolysis apparatus employed in semiconductor manufacturing technology.

The heater 4 heats the substrate 16 by heating the susceptor 15 in the chamber 2. The heater 4 is disposed below the chamber 2. The heater 4 may be a light source that emits infrared rays, which is employed as a heating means in semiconductor manufacturing technology. The heating output of the heater 4 can be controlled by the control unit 14.

  The susceptor 15 is made of SiC and has a shape corresponding to the shape of the substrate 16. The susceptor 15 is disposed concentrically with the bottom of the chamber 2. The susceptor 15 holds the substrate 16 so that the surface of the substrate 16 is substantially parallel to the surface of the diffuser plate 31. The susceptor 15 is connected to the thermocouple 13. The thermocouple 13 converts the detected heat (temperature) of the susceptor 15 to control the temperature of the susceptor 15 into an electric signal and supplies the electric signal to the controller 14. The control unit 14 supplies a heating output control signal based on the electric signal to the heater 4.

  An example of the operation of the resist removal apparatus 1 will be described with reference to FIG.

  For example, ethylene gas is supplied from the gas cylinder 6 as an unsaturated hydrocarbon by the suction force of the vacuum pump 3 with the exhaust valve 10 set to fully open, and the ozone generator 8 supplies an ultrahigh-concentration ozone gas (ozone concentration≈100%). ) Is provided in the chamber 2. The substrate 16 is held at 80 ° C. or lower by the susceptor 15 heated by the heater 4. The ethylene gas flows through the space 42 of the shower head 12 and then is discharged into the chamber 2 from the hole 39 of the diffuser plate 31. On the other hand, the ultra-high-concentration ozone gas flows through the space 41 of the shower head 12 and then is discharged into the chamber 2 from the hole 38 through the air diffuser 38. The exhaust valve 10 is controlled such that the opening is adjusted and the internal pressure of the chamber 2 (measured value of the pressure gauge 18) becomes 400 Pa, for example. It is processed for about 5 minutes in this state. In this processing time zone, the temperature of the substrate 16 on the susceptor 15 rises due to self-heating, but is controlled to 90 ° C. or lower. Thereafter, the supply of ultra-high concentration ozone gas and ethylene gas is stopped. In the reaction process in the chamber 2, the resist 17 is decomposed by various radicals including hydrogen radicals generated by the unsaturated hydrocarbon and ozone into which the resist 17 is introduced (The Chemical Society of Japan, Quarterly Chemical Review, No. 7, Chemistry of active oxygen, published on April 20, 1990, pp. 36-37). In such a process, the resist component made of hydrocarbons becomes exhaust gas made of carbon dioxide and water and is discharged from the chamber 2 through the pipe 9.

  FIG. 3 shows an example of changes over time in the susceptor temperature and the chamber pressure based on the above operation example. The temperature of the susceptor 15 is stable at about 80 ° C. before the introduction of the ultra-high concentration ozone gas from the ozone generator 8 (ozone generator MPOG-HM1A1). It was confirmed to end at less than 90 ° C.

FIG. 4 is an appearance photograph of the substrate surface processed by the resist removal method according to the embodiment of the resist removal apparatus 1. Specifically, the appearance when the surface of the Si substrate having the resist for KrF implanted with 5E15 / cm ² (5 × 10 ¹⁵ / cm ² ) of P (phosphorus) is processed based on the time chart shown in FIG. Show photos. The popping phenomenon did not occur when the temperature of the susceptor 15 was about 90 ° C. Such a low temperature treatment has a very small influence on the substrate.

  As is clear from the above description, the resist removing apparatus 1 can remove the resist 17 while reducing damage to the underlying substrate 16. Further, since the resist removing apparatus 1 does not use water vapor in the process of removing the resist, the structure and handling of the apparatus becomes easy. Furthermore, in the case of a high dose ion implantation resist, it can be removed while reliably suppressing the popping phenomenon. Further, even if the underlying substrate 16 is easily oxidized (for example, Cu wiring), the oxidation can be minimized. Furthermore, since ozone gas and unsaturated hydrocarbon gas are supplied by the shower head method, even a large area substrate can be processed uniformly. The means for heating the susceptor 15 is not limited to the heater 4, and various heating means such as a light source that emits infrared light or induction heating may be used. The gas reacted in the chamber 2 is exhausted by the vacuum pump 3, and the exhaust line (pipe 9) of the chamber 2 is evenly arranged at the center of the lower part of the chamber 2 or at the lower part of the periphery of the susceptor 15. Therefore, the flow of the reaction gas on the substrate becomes radial, which contributes to the improvement of in-plane uniformity of the removal rate.

Sectional drawing which showed schematic structure of the resist removal apparatus which concerns on embodiment of invention. The top view which showed the example of arrangement | positioning of the hole of the diffuser plate with which the resist removal apparatus which concerns on embodiment of this invention was equipped. The change with time of the susceptor temperature and the chamber pressure of the resist removing apparatus according to the embodiment of the invention. The external appearance photograph of the substrate surface processed by the resist removal method which concerns on the Example of invention. Molecular structure of various resists.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Resist removal apparatus 2 ... Chamber 3 ... Vacuum pump 4 ... Heater 6 ... Gas cylinder 8 ... Ozone generator 10 ... Exhaust valve 12 ... Shower head, 31 ... Air diffuser plate, 32 ... Air diffuser, 33 ... Frame part, 34 ... Spacer, 35 ... partition plate, 36 ... partition plate frame, 37 ... lid, 38, 39 ... hole 13 ... thermocouple 14 ... control unit 15 ... susceptor 16 ... substrate, 17 ... resist 18 ... pressure gauge

Claims (5)

A chamber in which the internal pressure is controlled to be lower than the atmospheric pressure so that the temperature of the substrate is 90 ° C. or lower in an atmosphere in which the substrate can be heated and plasma is not generated ;
And a shower head for removing the resist on the substrate to ozone gas and the unsaturated hydrocarbon gas in the chamber is supplied to the substrate,
The shower head is
An ozone gas chamber for circulating the ozone gas;
An unsaturated hydrocarbon gas chamber for circulating the unsaturated hydrocarbon gas;
A resist removing apparatus comprising: an air diffuser that individually diffuses ozone gas in the ozone gas chamber and unsaturated hydrocarbon gas in the unsaturated hydrocarbon gas chamber to the surface of the substrate. The resist removal apparatus according to claim 1, wherein the ozone gas chamber and the unsaturated hydrocarbon gas chamber are arranged hierarchically. The resist removing apparatus according to claim 2, wherein the diffuser member includes a plurality of holes through which the ozone gas is discharged and holes through which the unsaturated hydrocarbon gas is discharged. The resist removing apparatus according to claim 3, wherein the hole through which the ozone gas is discharged and the hole through which the unsaturated hydrocarbon gas is discharged are arranged at equal intervals. The ozone gas chamber is disposed at an upper stage or a lower stage than the unsaturated hydrocarbon gas chamber,
The ozone gas chamber and the unsaturated hydrocarbon gas chamber are partitioned by a partition plate, and a pipe for supplying the ozone gas or the unsaturated hydrocarbon gas is connected to the partition plate,
The resist removing apparatus according to claim 3 or 4, wherein a lower end of the pipe is connected to a hole through which the ozone gas or unsaturated hydrocarbon gas of the air diffuser is discharged.