Device for irradiating a substrate

Abstract

Known apparatuses for irradiating a substrate include a housing and, within the housing, a receptacle for the substrate having a circular irradiation surface and a first emitter for generating optical radiation having a first emitter tube arranged in a plane of curvature extending parallel to the irradiation surface and having an emitter tube end, whereby the receptacle and the first emitter can be moved with respect to each other. In these apparatuses, the irradiation surface includes first and second semi-circular surface portions. An improvement of the known apparatuses, which enables the substrate to have a rotationally symmetrical, homogeneous temperature distribution while keeping the complexity of design and control technology minimal, provides a first emitter tube having a curved illumination length section, extending with a mirror symmetrical-oval basic shape in the plane of curvature, wherein the first illumination length section is associated essentially with one of the semicircular surface portions.

Claims

1. An apparatus for irradiating a substrate, the apparatus comprising a housing and, within the housing, a receptacle for the substrate to be irradiated, the substrate having a circular irradiation surface comprising a first semi-circular surface portion and a second semi-circular surface portion, a first emitter to generate optical radiation, the first emitter having a first emitter tube arranged in a plane of curvature extending parallel to the circular irradiation surface and having an emitter tube end through which a power supply is guided, wherein the receptacle and the first emitter are rotatable with respect to each other about a rotational axis, wherein the first emitter tube has a curved illumination length section extending with a mirror symmetrical-oval basic shape in the plane of curvature, and wherein the curved illumination length section is associated with one of the semicircular surface portions.

2. The apparatus according to claim 1, wherein the curved illumination length section of the first emitter comprises multiple arcuate curved sections each having a radius of curvature, wherein the curved illumination length section, as seen from the emitter tube end, comprises, in succession, a first curved section having a curvature to the left and a first radius of curvature, a second curved section having a curvature to the right and a second radius of curvature, a third curved section having a curvature to the right and a third radius of curvature, a fourth curved section having a curvature to the right and the second radius of curvature, and a fifth curved section having a curvature to the left and the first radius of curvature, and wherein the third radius of curvature is larger by at least a factor of three than the first and the second radii of curvature.

3. The apparatus according to claim 2, wherein the first and the second curved sections as well as the fourth and the fifth curved sections are spaced from each other by a linear emitter tube section.

4. The apparatus according to claim 1, wherein the first emitter tube has an emitter tube length, and wherein the curved illumination length section of the first emitter accounts for at least 75% of the emitter tube length.

5. The apparatus according to claim 4, wherein the curved illumination length section of the first emitter accounts for at least 90% of the emitter tube length.

6. The apparatus according to claim 1, wherein the circular irradiation surface comprises an inner irradiation zone having a form of a circular surface and a ring-shaped outer irradiation zone surrounding the inner irradiation zone, wherein the circular inner irradiation zone and the ring-shaped outer irradiation zone have the same surface area, and wherein 40% to 70% of the length of the curved illumination length section of the first emitter are associated with the outer ring-shaped irradiation zone.

7. The apparatus according to claim 1, wherein the curved illumination length section of the first emitter is arranged exclusively over the first semicircular surface portion.

8. The apparatus according to claim 2, wherein the first emitter tube has a first emitter tube diameter, and wherein the first and the second radius of curvature of the first emitter tube are at least 1.0 times the first emitter tube diameter.

9. The apparatus according to claim 8, wherein the first and the second radius of curvature of the first emitter tube are at least 1.5 times the first emitter tube diameter.

10. The apparatus according to claim 1, further comprising a reflector within the housing to reflect the optical radiation.

11. A method for processing semiconductor wafers, the method comprising irradiating a semiconductor wafer substrate using the apparatus according to claim 1, wherein the first emitter is an infrared emitter.

12. A method for curing coatings on optical storage media or semiconductor wafers, the method comprising irradiating a storage media substrate or a semiconductor wafer substrate using the apparatus according to claim 1, wherein the first emitter is a gas discharge emitter having a noble gas filling.

13. An emitter for generating optical radiation, the emitter comprising an emitter tube curved in a plane of curvature and having an emitter tube end through which a power supply is guided, the emitter tube comprising multiple arcuate curved sections each having a radius of curvature, the emitter tube having a curved illumination length section extending with a mirror symmetrical-oval basic shape in the plane of curvature, wherein the curved illumination length section, as seen from the emitter tube end, comprises, in succession, a first curved section having a curvature to the left and a first radius of curvature, a second curved section having a curvature to the right and a second radius of curvature, a third curved section having a curvature to the right and a third radius of curvature, a fourth curved section having a curvature to the right and the second radius of curvature, and a fifth curved section having a curvature to the left and the first radius of curvature, and wherein the third radius of curvature is larger by at least a factor of three than the first and the second radii of curvature, the emitter being rotatable about a rotational axis with respect to a receptacle toward which the generated optical radiation is emitted.

14. The emitter according to claim 13, wherein the first and the second curved sections, as well as the fourth and the fifth curved sections, are spaced from each other by a linear emitter tube section.

15. The emitter according to claim 13, wherein the first emitter tube has an emitter tube length, and wherein the curved illumination length section accounts for at least 75% of the emitter tube length.

16. The emitter according to claim 15, wherein the curved illumination length section accounts for at least 90% of the emitter tube length.

17. The emitter according to claim 13, wherein the emitter tube has an emitter tube diameter, and wherein the first and the second radii of curvature of the emitter tube are at least 1.0 times the diameter of the first emitter tube.

18. The emitter according to claim 17, wherein the first and the second radii of curvature of the emitter tube are at least 1.5 times the diameter of the first emitter tube.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

(2) FIG. 1 shows a first embodiment of the apparatus according to the invention for irradiating a substrate having an optical emitter that comprises a mirror-symmetrical-oval illumination length section;

(3) FIG. 2 shows a spatial view of a second embodiment of the apparatus according to the invention having an irradiation space situated between the irradiation surface and the plane of curvature, wherein the irradiation surface comprises a circular inner irradiation zone and a ring-shaped outer irradiation zone;

(4) FIG. 3 shows first embodiment of an emitter for generating optical radiation according to the invention for insertion into an apparatus according to the invention for irradiating a substrate; and

(5) FIG. 4 shows a second embodiment of an emitter for generating optical radiation according to the invention for insertion into an apparatus according to the invention for irradiating a substrate.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a schematic top view of a first embodiment of the irradiation apparatus according to the invention for the processing of semiconductor wafers, to which, altogether, reference number 100 is assigned. The apparatus 100 comprises a housing 101 and, inside the housing 101, a receptacle 102, which can be rotated about a rotation axis (not shown), for a substrate 103 to be irradiated, a thermal infrared emitter 105 having an emitter tube 106 and a passage 120 for a dosing apparatus (not shown).

(7) The receptacle 102 comprises a circular irradiation surface 104, which is sub-divided into a first semi-circular surface portion 104a and a second semi-circular surface portion 104b. Furthermore, the irradiation surface comprises an inner irradiation zone 116 in the form of a circular surface and a ring-shaped outer irradiation zone 117 of the same surface area.

(8) The thermal infrared emitter 105 inside the housing 101 is arranged in a plane of curvature that extends parallel to the irradiation surface 104. Gas-tight seals 108a, 108b of the emitter tube 106, through which the power supplies 109a, 109b are respectively guided, are provided at both ends of the emitter tube 106. A layer of SiO.sub.2 acting as a reflector is applied to the side of the emitter tube 106 that faces away from the substrate. The emitter tube 106 further comprises multiple arcuate curved sections 110, 111, 112, 113, 114.

(9) Viewed from the center 115 of the apparatus 100, the curved section 110 comprises a curvature to the left with a radius of curvature of 25 mm, the curved section 111 comprises a curvature to the right with a radius of curvature of 25 mm, the curved section 112 comprises a curvature to the right with a radius of curvature of 180 mm, the curved section 113 comprises a curvature to the right with a radius of curvature of 25 mm, and the curved section 114 comprises a curvature to the left with a radius of curvature of 25 mm.

(10) The arcuate curved sections 110, 111, 112, 113, 114 form the illumination length section of the infrared emitter 105. The illumination length section extends in the plane of curvature with a mirror symmetrical-oval shape; it is arranged exclusively over the semi-circular surface portion 104b and accounts for 90% of the emitter tube length. In this embodiment, 65% of the length of the emitter tube 106 is associated with the outer ring-shaped irradiation zone 117.

(11) A window 107 made of quartz glass is arranged between the plane of curvature and the irradiation surface 104.

(12) In an alternative embodiment, the invention provides the apparatus 100 to comprise a second infrared emitter (not shown) which is also arranged in the plane of curvature. The second infrared emitter is designed alike the infrared emitter 105; it is arranged in the plane of curvature with an appropriate offset with respect to the infrared emitter 105 such that the illumination length sections of the infrared emitter 105 and of the second infrared emitter are point-symmetrical with respect to each other.

(13) FIG. 2 shows a schematic view of a second embodiment of the apparatus according to the invention for irradiating a substrate 200. The apparatus 200 comprises a receptacle for the substrate to be irradiated having an irradiation surface 202 and a plane of curvature 201.

(14) The plane of curvature 201 of the apparatus 200 is shown as a circle with the center 207 in FIG. 2. In the plane of curvature 201, the emitter tube of a curved infrared emitter extends in the form of an illumination length section that extends with mirror symmetrical-oval shape in the plane of curvature (not shown).

(15) The irradiation surface 202 is arranged parallel to the plane of curvature 201; it is also shown as a circle. The center 208 of the circular surface of the irradiation surface 202 and the center 207 define a rotation axis 209 about which the infrared emitter and the receptacle for the substrate to be irradiated can be moved with respect to each other. The irradiation surface 202 comprises a first semi-circular surface portion 203 and a second semi-circular surface portion 204. Moreover, the irradiation surface 202 comprises an inner irradiation zone 205 in the form of a circular surface having a radius of r.sub.i. The inner irradiation zone 205 is surrounded by an outer ring-shaped irradiation zone 206, whose radius is denoted as r.sub.a. The inner radiation zone 205 and the outer ring-shaped irradiation zone have the same surface area. Accordingly, the relation of the radii r.sub.i and r.sub.a is described by the following mathematical relationship: r.sub.a=r.sub.i*√2.

(16) For a better overview, the substrate to be irradiated is drawn in FIG. 2 as a cross-hatched circular surface 210 having a radius r.

(17) The irradiation space of the apparatus 200 is situated between the plane of curvature 201 and the irradiation surface 202.

(18) FIG. 3 shows a first embodiment of the thermal infrared emitter 300 according to the invention in a top view (A), side view (B), and in a spatial view (C). The thermal infrared emitter 300 is well-suited for use in the apparatus 100, 200 according to the invention according to FIG. 1 and/or FIG. 2.

(19) The infrared emitter 300 comprises an emitter tube 301 that is curved in a plane of curvature and has multiple curved sections 310, 311, 312, 313, 314. The profile of curvature of the emitter tube 301 is given by the dashed line 320. The radii of curvature are R.sub.1=25 mm, R.sub.2=25 mm, R.sub.3=130 mm, R.sub.4=25 mm, and R.sub.5=25 mm. A tungsten filament (not shown) is arranged inside the emitter tube 301 as a thermal emitter. For electrical contacting of the tungsten filament, gas-tight seals 302a, 302b, through which the respective the power supplies are guided, are provided at both ends of the emitter tube 301. The gas-tight seals 302a, 302b are situated at a distance a of 70 mm. The length b, c of the current supply leads 305a, 305b is 200 mm. The emitter dimensions d, e, and f are 71 mm, 116 mm, and 4 mm, respectively. The emitter tube 301 comprises an emitter tube outer diameter of 10 mm, and is filled with argon. The filling pressure is 800 mbar at room temperature.

(20) The emitter 300 has a rated voltage of 360 V and a rated power of 2,790 W. The length of the tungsten filament is 465 mm. Accordingly, the specific power of the emitter 300 based on the length of the filament at the rated voltage is 60 W/cm. The filament temperature at the rated voltage is 1,600° C.

(21) An emitter layer made of opaque, diffuse scattering quartz glass is applied to one side of the emitter tube 301 (QRC® made by Heraeus Noblelight).

(22) Moreover, FIG. 4 shows a second embodiment of the emitter according to the invention in the form of the thermal infrared emitter 400 in a top view (A), side view (B), and in a spatial view (C). The thermal infrared emitter 400 is well-suited for use in the apparatus 100, 200 according to the invention according to FIG. 1 and/or FIG. 2.

(23) The infrared emitter 400 comprises an emitter tube 401 that is curved in a plane of curvature and has multiple curved sections 410, 411, 412, 413, 414. The profile of curvature of the emitter tube 401 is given by the dashed line 420. The radii of curvature are R.sub.1=25 mm; R.sub.2=25 mm; R.sub.3=130 mm; R.sub.4=25 mm and R.sub.5=25 mm. A tungsten filament (not shown) is arranged inside the emitter tube 401 as a thermal emitter. For electrical contacting of the tungsten filament, gas-tight seals 402a, 402b, through which the respective the power supplies are guided, are provided at both ends of the emitter tube 401. The gas-tight seals 402a, 402b are situated at a distance a of 70 mm. The length b, c of the current supply leads 405a, 405b is 200 mm. The emitter dimensions d, e, h, and g are 75 mm, 112 mm, 43 mm, and 32 mm, respectively. The emitter tube 401 comprises an emitter tube outer diameter of 10 mm, and is filled with argon. The filling pressure is 800 mbar at room temperature.

(24) The emitter 400 has a rated voltage of 360 V and a rated power of 4,300 W. The length of the tungsten filament is 430 mm. Accordingly, the specific power of the emitter 400 based on the length of the filament at the rated voltage is 100 W/cm. The filament temperature at the rated voltage is 2,600° C.

(25) An emitter layer made of opaque, diffuse scattering quartz glass is applied to one side of the emitter tube 401 (QRC® made by Heraeus Noblelight).

Example 1a

(26) The use of the apparatus according to the invention for curing protective lacquer on data media blanks (CD, DVD, Blue Ray, etc.) by spin coating is described in the following.

(27) The medium to be cured (a lacquer, an epoxy resin or the like) is added as a fluid to the center of the rapidly rotating data medium such that it is homogeneously distributed on the surface of the data medium due to the rotation of the data medium. Once the surface is wetted completely and the layer is almost homogeneous, the fluid is subjected to intense radiation, which enables the cross-linking of monomers of the fluid.

(28) An emitter according to the invention in the form of a discharge lamp, which, in normal operation, emits a large fraction of its radiation intensity in the range of the effective wavelength for cross-linking, is used for curing of the protective lacquer.

(29) The optical emitter is arranged in a plane parallel to the surface of the data medium at a distance of 20 mm. The distance is defined, on the one hand, through the center of the discharge in the emitter tube and, on the other hand, by the surface of the data medium. The electrodes of the optical emitter are arranged appropriately such that the contact points of the arc of the emitter in new condition are situated on a plane which also includes the rotational axis.

(30) The emitter tube of the optical emitter is made of a quartz glass tube of 1*6 mm, where the first number (“1”) is the wall thickness in mm, and the second number (“6”) is the external diameter in mm. The bend radii of the emitter tube are at least 10 mm.

(31) In order for the cured coating to have a homogeneous layer thickness, the irradiation apparatus comprises an opening for dosing the fluid in the region of the rotational axis of the data medium. The apparatus for accommodating and rotating the data medium is located below, and the irradiation apparatus is situated above, the plane defined by the data medium.

(32) The housing of the irradiation apparatus consists of a body made of aluminum having, on the emitter side, high quality surfaces reflecting the optical radiation. The housing fully encloses the optical emitter. The electrical leads are also arranged in the housing. Moreover, not only the leads for the electrical connections and the passage for the dosing apparatus, but also supply and discharge lines for a cooling gas are introduced into the aluminum body, such that the housing can be actively cooled using up to 10 l/min of nitrogen. A window made of quartz glass 2.0 mm in thickness is placed between the optical emitter and the data medium. The quartz glass window is attached to the aluminum body in the absence of an additional seal; the gap widths are consistently less than 0.1 mm. In this context, the quartz glass has a thermal shock resistance of 1,000 K s.sup.−1, aluminum of better than 10 K s.sup.−1, the thermal mass (defined as density*specific heat at 20° C.) of aluminum is 2.42 J cm.sup.−2 K.sup.−1, of quartz better than 1.8 J cm.sup.−2 K.sup.−1.

Example 1b

(33) The use of the apparatus according to the invention for curing protective lacquer on data media blanks (CD, DVD, Blue Ray, etc.) by spin coating is described as a further exemplary embodiment in the following.

(34) Example 1b corresponds to Example 1a except for the following differences:

(35) The apparatus according to Example 1b differs from the apparatus of Example 1a in that the housing does not enclose the optical emitter completely. The emitter ends of the optical emitter are guided out of the irradiation space. They are sealed such as to be water-tight in the region, in which they are guided out of the irradiation space. The electrical leads are arranged outside the housing. Furthermore, inlets and outlets for a cooling fluid are introduced in the aluminum body such that the housing can be actively cooled with up to 61/min deionized water. In order to avoid leakage of cooling fluid, the quartz glass window is mounted on the aluminum body of the housing with an additional Viton seal.

Example 2

(36) Example 2 relates to the application of the apparatus according to the invention according to FIG. 1 in a process for curing protective lacquer on data medium blanks (CD, DVD, Blue Ray, etc.) by spin coating.

(37) Example 2 corresponds to Example 1a except for the following differences:

(38) The housing of the irradiation apparatus is a body made of quartz glass, which is coated on the emitter side with a layer of opaque, diffuse reflective quartz glass (QRC® made by Heraeus Noblelight).

(39) In addition to leads for the electrical connections and the passage for the dosing apparatus, inlets and outlets for a cooling gas are introduced into the housing such that the housing can be cooled actively with up to 21/min of nitrogen.

Example 3a

(40) In the following, the use of the apparatus according to the invention for cleaning of silicon wafers with a diameter of 12 inches, or 300 mm, is described.

(41) For this purpose, a cleaning solution that comprises a solvent (e.g., water, methanol, isopropanol, acetone), which can also contain active substances (e.g., sulfuric acid, phosphoric acid, ammonia, aqua regia, hydrofluoric acid), is applied to the wafer from above. To render the process particularly intense or quick, the cleaning solution is placed on the wafer while it has a temperature close to the evaporation point of the liquid. In order to maintain a uniform temperature on the wafer and to counteract cooling by removing heat of evaporation, the wafer is irradiated with infrared radiation.

(42) Infrared radiation in the range of <1,100 nm is preferably used if the wafer is to be heated, whereas infrared radiation >1,500 nm is preferably used if the cleaning solution is to be heated.

(43) In the present case, the following arrangement is selected:

(44) An apparatus that places the cleaning solution on the wafer is attached above the fast-rotating wafer (>100 min.sup.−1); otherwise, the wafer is exposed to a gas flow of low turbulence from above.

(45) Situated below the wafer, there is an apparatus for accommodation of the wafer by means of pins; concurrently, this apparatus makes the wafer rotate. Moreover, the irradiation apparatus is situated between the rotary apparatus and the wafer, but is at rest.

(46) The housing of the irradiation apparatus consists of an opaque glass ceramics (e.g., MACOR™ made by Corning) and is made in one piece. Supply leads for the electrical connections of the emitter and channels for the supply of cooling gas are provided. A pane of quartz glass (e.g., GE 200 or equivalent grade) with a thickness of 1.5 mm is provided as an optical window. The window is placed with a gap width of 0.15 mm, wherein the gap is defined by means of some suitable contact points projecting from the housing such that a cooling gas rate of 1.3 l/min is attained. Nitrogen is provided as the cooling gas.

(47) The thermal mass of MACOR and of quartz glass is 2.0 J cm.sup.−2K.sup.−1 and less than 1.8 J cm.sup.−2 K.sup.−1, respectively.

(48) An optical emitter according to FIG. 4 is inserted into the housing.

Example 3b

(49) Example 3b describes an alternative embodiment of an apparatus according to the invention and the use thereof for cleaning silicon wafers having a diameter of 12 inches, or 300 mm.

(50) Example 3b corresponds to Example 3a except for the following differences:

(51) The housing is made of quartz glass (e.g., 7940 made by Corning) in one piece. Supply leads for the electrical connections of the emitter and channels for the supply and discharge of cooling gas are provided. A pane made of quartz glass having a thickness of 1.5 mm, which is mounted without a defined gap, is provided as the optical window.

(52) Nitrogen is provided as the cooling gas. A cooling gas rate of 1.0 l/min is attained.

(53) The optical emitter used presently is the emitter from FIG. 3.

(54) It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the invention as defined by the appended claims.