SUBSTRATE ANALYZING METHOD AND SUBSTRATE ANALYZING DEVICE

Abstract

A substrate analysis method using a nozzle for substrate analysis which discharges an analysis liquid from a tip thereof, scans a substrate surface with a discharged analysis liquid, and sucks the analysis liquid. This is done by arranging a liquid catch plate that catches the discharged analysis liquid, thus retaining analysis liquid discharged between the nozzle tip and the liquid catch plate; positioning the substrate so that the end part thereof can be inserted between the nozzle tip and the liquid catch plate; bringing the end part of the substrate into contact with analysis liquid retained between the nozzle tip and liquid catch plate; and moving the nozzle and liquid catch plate concurrently along a periphery of the substrate, while keeping the end part of the substrate in contact with the analysis liquid, to analyze the end part of the substrate.

Claims

1. An analysis method of a substrate by use of a nozzle for substrate analysis, which discharges an analysis liquid from a tip of the nozzle, scans a surface of the substrate with a discharged analysis liquid, and then sucks the analysis liquid, comprising the steps of: arranging, opposite to a nozzle tip, a liquid catch plate that catches the discharged analysis liquid, to thereby retain the analysis liquid discharged from the tip between the nozzle tip and the liquid catch plate; positioning the substrate so that the end part thereof can be inserted between the nozzle tip and the liquid catch plate; bringing the end part of the substrate into contact with the analysis liquid retained between the nozzle tip and the liquid catch plate; and moving the nozzle and the liquid catch plate concurrently along a periphery of the substrate, while keeping the end part of the substrate in contact with the analysis liquid, to thereby analyze the end part of the substrate.

2. The analysis method of a substrate according to claim 1, wherein the liquid catch plate is hydrophobic.

3. The analysis method of a substrate according to claim 1, wherein the nozzle is constituted by a triple concentric tube that includes a tube through which the analysis liquid is discharged and sucked; a first outer tube arranged around an outer circumference of the tube so as to surround the analysis liquid dragged for scanning; and a second outer tube arranged around an outer circumference of the first outer tube, and the nozzle further includes a first exhaust unit having an exhaust path arranged between the tube and the first outer tube; and a second exhaust unit having an exhaust path arranged between the first outer tube and the second outer tube.

4. The analysis method of a substrate according to claim 1, wherein the nozzle is constituted by a dual concentric tube that includes: a nozzle body through which the analysis liquid is discharged and sucked; and an outer tube arranged around an outer circumference of the nozzle body so as to surround the analysis liquid dragged for scanning, and the nozzle further includes an exhaust unit having an exhaust path arranged between the nozzle body and the outer tube.

5. A substrate analyzer comprising a nozzle for substrate analysis which discharges an analysis liquid from a tip of the nozzle, scans a substrate surface with a discharged analysis liquid, and then sucks the analysis liquid, comprising: a nozzle for substrate analysis, which is constituted by a triple concentric tube that includes a tube through which the analysis liquid is discharged and sucked; a first outer tube arranged around an outer circumference of the tube so as to surround the analysis liquid dragged for scanning; and a second outer tube arranged around an outer circumference of the first outer tube, wherein the nozzle further includes a first exhaust unit having an exhaust path arranged between the tube and the first outer tube; and a second exhaust unit having an exhaust path arranged between the first outer tube and the second outer tube; a liquid catch plate control unit that arranges, opposite to the nozzle tip, a liquid catch plate that catches the analysis liquid discharged through the tube; and a drive unit capable of synchronously moving the nozzle and the liquid catch plate relative to the substrate.

6. A substrate analyzer comprising a nozzle for substrate analysis which discharges an analysis liquid from a tip of the nozzle, scans a substrate surface with a discharged analysis liquid, and then sucks the analysis liquid, comprising: a nozzle for substrate analysis, which is constituted by a dual concentric tube that includes a nozzle body through which the analysis liquid is discharged and sucked; and an outer tube arranged around an outer circumference of the nozzle body so as to surround the analysis liquid dragged for scanning, and the nozzle further includes an exhaust unit having an exhaust path arranged between the nozzle body and the outer tube; a liquid catch plate control unit that arranges, opposite to the nozzle tip, a liquid catch plate that catches the analysis liquid discharged through the nozzle body; and a drive unit capable of synchronously moving the nozzle and the liquid catch plate relative to the substrate.

7. The analysis method of a substrate according to claim 2, wherein the nozzle is constituted by a triple concentric tube that includes a tube through which the analysis liquid is discharged and sucked; a first outer tube arranged around an outer circumference of the tube so as to surround the analysis liquid dragged for scanning; and a second outer tube arranged around an outer circumference of the first outer tube, and the nozzle further includes a first exhaust unit having an exhaust path arranged between the tube and the first outer tube; and a second exhaust unit having an exhaust path arranged between the first outer tube and the second outer tube.

8. The analysis method of a substrate according to claim 2, wherein the nozzle is constituted by a dual concentric tube that includes: a nozzle body through which the analysis liquid is discharged and sucked; and an outer tube arranged around an outer circumference of the nozzle body so as to surround the analysis liquid dragged for scanning, and the nozzle further includes an exhaust unit having an exhaust path arranged between the nozzle body and the outer tube.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a cross-sectional view that illustrates an end part of a substrate.

[0025] FIG. 2 is a schematic cross-sectional view that illustrates a substrate analyzer of this embodiment.

[0026] FIG. 3 is a plan view that illustrates an edge plate.

[0027] FIG. 4 is a schematic cross-sectional view that illustrates a mode of analysis of the end part of the substrate.

[0028] FIG. 5 is a schematic cross-sectional view that illustrates a mode of analysis of the end part of the substrate.

DESCRIPTION OF EMBODIMENT

[0029] Embodiments of the present invention will be explained below. FIG. 2 shows a schematic cross-sectional view that illustrates a substrate analyzer of this embodiment.

[0030] A nozzle 100 illustrated in FIG. 2 is constituted by a triple concentric tube that includes a tube 110, a first outer tube 120 arranged around an outer circumference of the tube 110, and a second outer tube 130 arranged around an outer circumference of the first outer tube 120. The tube 110 has a syringe pump (not illustrated) connected thereto, enabling suction and discharge of an analysis liquid through the tube 110.

[0031] The first outer tube 120 has arranged thereto a first exhaust unit 121 which is connected to an evacuation pump (not illustrated), making it possible to keep a space (first exhaust path) formed between the tube 110 and the first outer tube 120 under a depressurized atmosphere. Similarly, a second exhaust unit 131, to which an evacuation pump (not illustrated) is connected, is arranged between the first outer tube 120 and the second outer tube 130, making it possible to keep a space (second exhaust path) formed between the first outer tube 120 and the second outer tube 130 under a depressurized atmosphere.

[0032] A substrate analyzer of this embodiment can analyze a substrate surface, according to the procedures below. The nozzle 100 is lowered toward a substrate W to an extent that the tip is not brought into contact with the substrate surface, and the analysis liquid is discharged through the tube 110. While this state is kept, the substrate surface is scanned with the analysis liquid. The nozzle is then stopped after completion of a predetermined scanning operation, the analysis liquid is sucked up through the tube 110, and collected into the syringe pump. The collected analysis liquid is analyzed by use of an analyzer such as ICP-MS.

[0033] Next, a case where the end part of the substrate is analyzed by use of the substrate analyzer of this embodiment will be explained. FIG. 3 is a plan view that illustrates a liquid catch plate 200. The liquid catch plate 200 is formed of PTFE, and has a circular plate 210 for catching an analysis liquid D, and a shaft 220 which is attached to the circular plate 210. When employing a triple concentric tube-type nozzle with a 20-mm second outer tube (18 mm in inner diameter, 22 mm in outer diameter), a 10-mm first outer tube (8 mm in inner diameter, 12 mm in outer diameter), and a ⅛-inch tube, then the diameter of the circular face 210 of the liquid catch plate 200 was set to 12 mm.

[0034] FIGS. 4 and 5 are schematic cross-sectional views that illustrate modes of analysis of the end part of the substrate. When the end part of the substrate is analyzed, the circular face 210 of the liquid catch plate 200 is first arranged below and in proximity to the nozzle tip. In this state, the analysis liquid is discharged through the tube 110. In this process, the first exhaust path and the second exhaust path are kept under a depressurized atmosphere. The analysis liquid D discharged through the tube 110 is controlled to be caught over the entire range of the circular face 210 of the liquid catch plate 200. The analysis liquid D discharged through the tube 110 then becomes retained between the nozzle tip and the liquid catch plate, by the action of surface tension and the depressurized atmosphere in the first exhaust path and the second exhaust path.

[0035] After the analysis liquid D is thus kept retained, the substrate W is then moved so as to bring the end part thereof into contact with the analysis liquid D. While the contact state of the end part of the substrate W is controlled, the bevel part B illustrated in FIG. 1 is analyzed (FIG. 4), or the edge part E is analyzed (FIG. 5).

[0036] Measurement results of the end part of the substrate W will be explained. A 12-inch silicon wafer was employed as a substrate to be analyzed. The substrate has a thickness of 0.775 mm±0.02 mm, with the circumferential end part processed by so-called beveling (chamfering). The analysis liquid was a mixed solution of 3 vol % hydrogen fluoride and 4 vol % hydrogen peroxide solutions, and for use, 1 mL of which was sucked up in the ⅛-inch tube of the nozzle.

[0037] The nozzle tip and the liquid catch plate were set 2.5 mm away from each other, and 200 μL of the analysis liquid was discharged through the ⅛-inch tube of the nozzle so as to allow the analysis liquid to be retained between the nozzle tip and the liquid catch plate. Now, any change in the distance between the nozzle tip and the liquid catch plate will need suited control of the volume of discharge of the analysis liquid, in which for a distance of 2 to 3 mm, the volume of discharge is controlled within the range of 100 to 300 μL.

[0038] With the analysis liquid retained between the nozzle tip and the liquid catch plate, the end part of the substrate was moved to an intermediate position between the nozzle tip and the liquid catch plate, where the end part of the substrate was brought into contact with the analysis liquid. Operation for such contact of the end part may be monitored under a microscope (under magnification). Now in a case where the bevel part B illustrated in FIG. 1 is to be analyzed, the end part of the substrate was brought into contact with the analysis liquid as illustrated in FIG. 4. While the state is kept, the nozzle and the liquid catch plate were synchronously moved relative to the substrate (30 mm/min), along the outer circumference of the substrate. (Moved at 5 mm/min, for hydrophilic wafer). Also during movement, the contact state of the end part of the substrate and the analysis liquid was monitored under a microscope. After the relative movement over a part to be analyzed, the analysis liquid was sucked up, and analyzed by ICP-MS.

[0039] Table 1 summarizes results of ICP-MS analysis, with a volume of collected analysis liquid of 300 μL, obtained after scanning the edge part of the 12-inch silicon wafer (with a total scanned area of the edge part of 7.3 cm.sup.2).

TABLE-US-00001 TABLE 1 Concentration in collected liquid Concentration Elements Mass number (g) (ppt) (atoms/cm.sup.2) Na 22.98977 5 5.38E+09 Mg 24.305 1.2 1.22E+09 Al 26.9815386 8 7.34E+09 K 39.0983 4 2.53E+09 Ca 40.078 6 3.70E+09 Cr 51.9961 5 2.38E+09 Mn 54.938045 0.7 3.15E+08 Fe 55.845 2 8.86E+08 Co 58.933195 0.2 8.40E+07 Ni 58.6934 1.3 5.48E+08 Cu 63.546 1 3.89E+08 Zn 65.409 3 1.13E+09 Zr 91.224 0.14 3.80E+07 Mo 95.94 0.8 2.06E+08 Sn 118.71 2 4.17E+08 Sb 121.76 1.43 2.91E+08 W 183.84 0.3 4.04E+07 Pb 207.2 0.1 1.19E+07

[0040] It was revealed from the analytical results of the end part of the substrate summarized in Table 1 that metal pollution only in the edge part of wafer can be easily analyzed.

[0041] This embodiment, although having exemplified above a case of silicon wafer, is applicable to various types of substrate with different materials and sizes. This embodiment is also applicable to both of hydrophobic and hydrophilic substrates. The analysis liquid can employ various types of solution other than the mixed solution of hydrogen fluoride and hydrogen peroxide, which include aqua regia-based solution (for precious metals to be analyzed) and nitric acid solution (for hydrophilic substrate to be analyzed).

REFERENCE SIGNS LIST

[0042] 1 Chamfered part [0043] 2 Outermost edge [0044] 100 Nozzle [0045] 110 Tube [0046] 120 First outer tube [0047] 130 Second outer tube [0048] B Bevel part [0049] E Edge part [0050] W Wafer [0051] D Analysis liquid