JP2009277753A - Manufacturing method of semiconductor device - Google Patents

Abstract

There is a demand for a cleaning method that does not depend on ashing conditions of a resist film and suppresses the occurrence of corrosion.
A conductive film (45) containing aluminum is formed on a semiconductor substrate. A resist pattern (48) is formed on the conductive film. Wiring (45a, 45b) is formed by etching the conductive film using a gas containing halogen using the resist pattern as a mask. After the wiring is formed, the resist pattern is removed. After removing the resist pattern, the surface on which the wiring is formed is treated with a chemical solution (62) to remove residues after removing the resist pattern. After the treatment with the chemical solution, the substrate surface is washed with warm water (63) of 40 ° C. or higher.
[Selection] Figure 1-2

Description

  The present invention relates to a method for manufacturing a semiconductor device including a step of cleaning a surface of a conductive film containing aluminum after patterning.

When a conductive film containing aluminum (Al) is etched using a halogen-based gas such as Cl ₂ or BCl ₃ , a chlorine-based residue remains on the surface of the conductive pattern even after the resist film is removed. Chlorine-based residues cause corrosion. If a mixed gas of O ₂ and CF ₄ is used during ashing of the resist film, Al halide is converted into water-soluble Al fluoride. After removing the resist film, the Al fluoride can be removed by washing with water (Patent Document 1).

When forming a wiring in which an Al-based conductive film and a Ti-based conductive film are laminated, the resist film is removed by ashing using O ₂ gas and fluorine-based gas, and then cold water and hot water are sequentially used. A method of washing with water is known (Patent Document 2). Ti fluoride is removed by cold water, and Al fluoride is removed by hot water.

  In addition, a TiN film used for an adhesion layer or the like may be formed by CVD using titanium tetrachloride and ammonia and then washed with pure water (Patent Document 3). By this pure water cleaning, chlorine contained in the TiN film can be removed.

Japanese Patent Laid-Open No. 6-84840 Japanese Patent Laid-Open No. 2000-232096 JP 2001-102444 A

  A cleaning method that does not depend on the ashing conditions of the resist film and suppresses the occurrence of corrosion is desired.

A method of manufacturing a semiconductor device for solving the above problems is as follows.
Forming a conductive film containing aluminum on a semiconductor substrate;
Forming a resist pattern on the conductive film;
Forming a wiring by etching the conductive film using a gas containing halogen using the resist pattern as a mask;
Removing the resist pattern after forming the wiring;
After removing the resist pattern, by treating the surface of the wiring and the substrate surface on which the wiring is formed with a chemical solution, removing the residue after removing the resist pattern;
After the treatment with the chemical solution, there is a step of washing the wiring and the substrate surface on which the wiring is formed with warm water.

  By using warm water in the water washing step, the occurrence of corrosion can be suppressed. Further, since the residue is removed by the chemical treatment, it is not necessary to employ special conditions that make it easy to remove the residue in the resist pattern removal step.

  1A to 1F are cross-sectional views of a semiconductor device manufactured by the manufacturing method according to the first embodiment in the middle of manufacturing.

  As shown in FIG. 1A, an element isolation insulating film 11 is formed on a surface layer portion of a semiconductor substrate 10 such as silicon to define an active region. In this active region, a MOS transistor 12 is formed. An interlayer insulating film 15 is formed on the semiconductor substrate 10 so as to cover the MOS transistor 12. Two conductive plugs 16 and 17 penetrating the interlayer insulating film 15 are connected to the source and drain of the MOS transistor 12, respectively.

  A second interlayer insulating film 18 is formed on the interlayer insulating film 15. The recesses formed in the interlayer insulating film 18 are filled with conductive patterns 19 and 20. The conductive patterns 19 and 20 are respectively connected to conductive plugs 16 and 17 disposed immediately below them.

  A third interlayer insulating film 25 is formed on the interlayer insulating film 18. In the interlayer insulating film 25, wirings 26 and 27 formed by a dual damascene method are arranged. The wirings 26 and 27 are connected to the conductive patterns 19 and 20, respectively.

  A fourth interlayer insulating film 30 is formed on the interlayer insulating film 25. For example, silicon oxide is used for the interlayer insulating film 30. Conductive plugs 31 and 32 are filled in the via holes formed in the interlayer insulating film 30, respectively. The conductive plugs 31 and 32 are connected to the wirings 26 and 27, respectively. For the conductive plugs 31 and 32, for example, tungsten (W) or the like is used.

  A conductive film 45 is formed on the interlayer insulating film 30. The conductive film 45 includes a lower glue film 40, a wiring film 41 thereon, and an upper glue film 42 thereon. The lower glue film 40 includes, for example, two layers of a Ti film having a thickness of 50 nm and a TiN film having a thickness of 30 nm. The wiring film 41 is formed of an AlCu alloy and has a thickness of, for example, 800 nm. The upper glue film 42 includes, for example, a single TiN film having a thickness of 70 nm. Note that the lower glue film 40 may be any one of a Ti film and a TiN film. The upper glue film 42 may have a two-layer structure of a Ti film and a TiN film. These films can be formed by sputtering, for example.

As shown in FIG. 1B, a resist pattern 48 corresponding to the planar shape of the wiring is formed on the conductive film 45. The conductive film 45 is etched using the resist pattern 48 as an etching mask. For the etching of the conductive film 45, dry etching using plasma 60 of a gas containing halogen, for example, an etching gas containing BCl ₃ , Cl ₂ , CHF ₃ , and Ar is applied. As an example, the flow rates of BCl ₃ , Cl ₂ , CHF ₃ , and Ar are 150 sccm, 150 sccm, 10 sccm, and 60 sccm, respectively.

  Thereby, the conductive film 45 is patterned to form wirings 45a and 45b. The wirings 45a and 45b are connected to the conductive plugs 31 and 32 thereunder, respectively.

As shown in FIG. 1C, the resist pattern 48 is removed by ashing using an ashing gas plasma 61 containing O ₂ gas and H ₂ O gas. As a result, the wirings 45a and 45b are exposed. At this time, chlorine and fluorine contained in the gas used for etching the conductive film 45 react with aluminum or the like, and a residue such as fluoride or chloride remains on the surface.

  As shown in FIG. 1D, the surface of the wirings 45a and 45b and the substrate surface on which these wirings are formed are treated with a chemical solution 62 to remove residues remaining on the substrate surface. An aqueous solution containing ammonium fluoride is used as the chemical solution.

  FIG. 2A shows a schematic diagram of a spin cleaning / drying apparatus used for chemical treatment. A table 107 is accommodated in a container 100 having a bottom surface and a side wall. The semiconductor substrate 10 is fixed to the upper surface of the table 107 by a vacuum chuck. The table 107 can rotate the semiconductor substrate 10 fixed by a vacuum chuck. A discharge port 101 is provided on the bottom surface of the container 100.

  The chemical liquid 62 is supplied to the surface of the semiconductor substrate 10 from the chemical liquid pipe 103. Pure water is supplied from the deionized water (pure water) pipe 104 to the surface of the semiconductor substrate 10. The upstream end of the pure water pipe 104 is connected to the temperature control tank 105. A heating lamp 108 is loaded in the temperature control tank 105. Pure water is introduced into the temperature control tank 105 from the pure water inflow pipe 106. The pure water introduced into the temperature control tank 105 is heated by the heating lamp 105 to become warm water. This hot water is supplied to the surface of the semiconductor substrate 10 via the pure water pipe 104.

  An elevating wall 102 is arranged in the vicinity of the side wall of the container 100. The elevating wall 102 includes an outer side wall 102a, an inner side wall 102b, and a connecting portion 102c that connects the two. The outer side wall 102a is disposed so as to surround the outer peripheral surface of the side wall of the container 100, and a gap is defined therebetween. The inner side wall 102b is disposed slightly inside the side wall of the container 100 in plan view. The outer side wall 102a and the inner side wall 102b are connected to each other by a connecting portion 102c at the upper edge. The lower end of the outer side wall 102a extends to a position lower than the lower end of the inner side wall 102b. The semiconductor substrate 10 is held at a position higher than the upper end of the side wall of the container 100.

  During the chemical treatment, the elevating wall 102 is raised until the lower end of the inner side wall 102b is positioned higher than the semiconductor substrate 10. At this time, the lower end of the outer side wall 102 a is disposed at a position lower than the upper end of the side wall of the container 100.

  The chemical solution is supplied from the chemical solution pipe 103 to the surface of the semiconductor substrate 10 while rotating the semiconductor substrate 10. The rotation speed of the semiconductor substrate 10 is set to 120 rpm, for example. The chemical liquid splashed to the outside from the edge of the semiconductor substrate 10 due to the centrifugal force collides with the side wall 102 a outside the elevating wall 102 and is discharged to the outside of the container 100.

  In addition, you may use the other chemical | medical solution which can remove the residue of a fluoride or a chloride. For example, an aqueous solution containing hydroxylamine may be used.

  As shown in FIGS. 1E and 2B, using the same apparatus as the spin cleaning apparatus used for the chemical treatment, heated pure water 63 is supplied to the substrate surface after the chemical treatment, and pure water cleaning is performed.

  As shown in FIG. 2B, during pure water cleaning, the elevating wall 102 is lowered until the lower end of the inner side wall 102 b is lower than the semiconductor substrate 10. While the semiconductor substrate 10 is rotated, heated pure water is supplied from the pure water pipe 104 to the surface of the semiconductor substrate 10. The rotation speed of the semiconductor substrate 10 is, for example, 300 rpm, and the supply time of pure water is in the range of 5 s to 90 s. The flow rate of pure water is 10 to 100 mL / min. A preferable range of the temperature of pure water will be described in detail later.

  The pure water splashed outward from the edge of the semiconductor substrate 10 collides with the inner side wall 102 b of the elevating wall 102 and drops into the container 100. The pure water in the container 100 is discharged out of the container through the discharge port 101. After the pure water cleaning, the rotational speed of the semiconductor substrate 10 is increased to 4000 rpm. The substrate surface is dried by maintaining this rotational speed for 20 seconds.

  After the chemical solution treatment shown in FIG. 1D, the chemical solution remains on the substrate surface. Residues and the like peeled off from the substrate float in the chemical solution. After the chemical treatment, cleaning with heated pure water can remove chemicals and residues remaining on the substrate from the substrate.

  As shown in FIG. 1F, after cleaning with pure water, an interlayer insulating film 50 is further formed on the interlayer insulating film 30 so as to cover the wirings 45a and 45b.

  With reference to FIG. 3A1-FIG. 3F2, the suitable temperature of the pure water used for a pure water washing | cleaning is demonstrated. FIG. 3A1 and FIG. 3A2 each show a location where foreign matter is detected after washing with pure water at room temperature and a micrograph of typical foreign matter. 3B1 and 3B2 are cleaned using pure water at 30 ° C., FIGS. 3C1 and 3C2 are cleaned using pure water at 40 ° C., and FIGS. 3D1 and 3D2 are 50 3E1 and FIG. 3E2 are cleaned using pure water at 60 ° C., and FIGS. 3F1 and 3F2 are cleaned using pure water at 70 ° C. After cleaning, a micrograph of a location where foreign matter is detected and a representative foreign matter is shown. Note that samples washed with pure water at room temperature, 50 ° C., 60 ° C., and 70 ° C. were left for 52 hours after washing and observed. Samples washed with pure water at 30 ° C. and 40 ° C. were left for 115 hours after washing and observed.

  When washed with pure water at room temperature (20 to 25 ° C.) and washed with pure water at 30 ° C., corrosion was observed as shown in FIGS. 3A2 and 3B2. About the sample wash | cleaned with the pure water of 40 degreeC, 50 degreeC, 60 degreeC, and 70 degreeC, the detected foreign material is a particle etc. and the corrosion was not observed. From the above evaluation results, it is understood that the occurrence of corrosion can be prevented by setting the temperature of pure water during pure water cleaning within the range of 40 ° C to 70 ° C. In addition, if the temperature of pure water is raised, the removal effect of a chemical | medical solution and a residue will increase. Therefore, the temperature of pure water may be higher than 70 ° C. and lower than the boiling point of water.

In the first embodiment, during the ashing of the resist pattern 48 shown in FIG. 1B, the plasma 61 of O ₂ gas and H ₂ O gas shown in FIG. 1C is used, and no fluorine-based gas is used. If a fluorine-based gas is used during ashing, a fine pattern is likely to collapse. In the first embodiment, it is not necessary to use a fluorine-based gas at the time of ashing, so that the collapse of a fine pattern can be suppressed.

  The second embodiment will be described with reference to FIGS. 4A and 4B. In the first embodiment, only heated pure water is used at the time of pure water cleaning, but two-fluid cleaning using heated pure water and gas, for example, nitrogen gas may be applied.

An example of a two-fluid nozzle is shown in FIGS. 4A and 4B. In the two-fluid nozzle 110 shown in FIG. 4A, pure water heated from the side is supplied to the N ₂ gas flow path. In the two-fluid nozzle 111 shown in FIG. 4B, N ₂ gas is supplied from the side to the flow path of the heated pure water. When two-fluid cleaning is used, nitrogen gas is mixed as bubbles in heated pure water, and pure water can be supplied to the surface of the object to be cleaned at high speed. For this reason, the cleaning ability can be increased.

  A third embodiment will be described with reference to FIG. In the first embodiment, a single wafer cleaning device is used, but in the third embodiment, a batch cleaning device is used.

  FIG. 5 shows a schematic view of a cleaning chamber of a batch type cleaning apparatus. A plurality of semiconductor wafers 10 to be cleaned are held parallel to each other on the wafer carrier 120. When the fixing bar 121 comes into contact with the edge of the semiconductor wafer 10, the position of the semiconductor wafer 10 is restrained so as not to drop off from the wafer carrier 120. The wafer carrier 120 and the fixing bar 121 rotate around a virtual straight line perpendicular to the surface of the semiconductor wafer 10 as a rotation center. Thereby, the plurality of semiconductor wafers 10 rotate.

  A chemical solution nozzle 130 and a pure water nozzle 131 are disposed on the side of the held semiconductor wafer 10. Each of the chemical solution nozzle 130 and the pure water nozzle 131 has a plurality of jet nozzles arranged in parallel to the direction in which the semiconductor wafers 10 are arranged. A chemical solution or pure water is jetted from these jets toward the semiconductor wafer 10.

  By introducing pure water heated in the temperature control tank 105 shown in FIG. 2A into the pure water nozzle 131, pure water cleaning using heated pure water is performed as in the first embodiment. It can be performed. As described above, cleaning with heated pure water can be applied to batch cleaning.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

(1A) to (1C) are cross-sectional views of the semiconductor device manufactured by the method according to the first embodiment in the course of manufacturing. (1D) to (1F) are cross-sectional views in the course of manufacturing a semiconductor device manufactured by the method according to the first embodiment. (2A) is a schematic view showing a state during chemical treatment of the single wafer cleaning apparatus used in the method according to the first embodiment, and (2B) is a schematic view showing a state during pure water cleaning. (3A1) and (3A2) are a plan view and a micrograph of typical defects when a defect is detected when cleaned with pure water at room temperature, and (3B1) and (3B2) are pure at 30 ° C. It is the top view which shows the defect detection location at the time of washing | cleaning with water, and the microscope picture of a typical defect, (3C1) and (3C2) are the planes which show the defect detection location at the time of washing | cleaning with 40 degreeC pure water. It is a figure and the microscope picture of a typical defect. (3D1) and (3D2) are a plan view showing a defect detection location when washed with pure water at 50 ° C., and a micrograph of typical defects. (3E1) and (3E2) are 60 ° C. It is the top view which shows the defect detection location at the time of washing | cleaning with a pure water, and the microscope picture of a typical defect, (3F1) and (3F2) show the defect detection location at the time of washing | cleaning with a pure water of 70 degreeC. It is a top view and the microscope picture of a typical defect. It is the schematic of the two-fluid nozzle used at the pure water washing | cleaning process of a 2nd Example. It is the schematic of the principal part of the batch type washing | cleaning apparatus used at the pure water washing | cleaning process of a 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor substrate 11 Element isolation insulating film 12 MOS transistor 15 1st interlayer insulating film 16, 17 Conductive plug 18 2nd interlayer insulating film 19, 20 Conductive pattern 25 3rd interlayer insulating film 26, 27 Wiring 30 Fourth interlayer insulating films 31, 32 Conductive plug 40 Lower glue film 41 Wiring film 42 Upper glue film 45 Conductive films 45a, 45b Wiring 50 Interlayer insulating film 60 Etching gas plasma 61 Ashing gas plasma 62 Chemical solution 63 Pure water 100 Container 101 Discharge port 102 Elevating wall 103 Chemical solution piping 104 Pure water piping 105 Temperature control tank 106 Pure water inflow piping 108 Heating lamps 110 and 111 Two-fluid nozzle 120 Wafer carrier 121 Fixed bar 130 Chemical solution nozzle 131 Pure water nozzle

Claims (4)

Forming a conductive film containing aluminum on a semiconductor substrate;
Forming a resist pattern on the conductive film;
Forming a wiring by etching the conductive film using a gas containing halogen using the resist pattern as a mask;
Removing the resist pattern after forming the wiring;
After removing the resist pattern, by treating the surface of the wiring and the substrate surface on which the wiring is formed with a chemical solution, removing the residue after removing the resist pattern;
A method of manufacturing a semiconductor device, comprising: a step of washing the wiring and the substrate surface on which the wiring is formed using hot water of 40 ° C. or higher after the treatment with the chemical solution.   The method of manufacturing a semiconductor device according to claim 1, wherein the chemical solution includes ammonium fluoride.   3. The method of manufacturing a semiconductor device according to claim 1, wherein in the washing step, the hot water is supplied to a surface on which the wiring is formed while rotating the semiconductor substrate.   4. The method for manufacturing a semiconductor device according to claim 1, wherein, in the step of removing the resist pattern, the resist pattern is ashed using plasma of a gas containing oxygen and not containing fluorine.