JP2947916B2 - Surface condition inspection device - Google Patents

Description

The present invention relates to a pellicle protective film surface and a reticle substrate when a pellicle protective film is mounted on a substrate such as a reticle or a photomask used in a semiconductor manufacturing process. The present invention relates to a surface state inspection apparatus represented by an apparatus for accurately detecting foreign matter such as fine dust adhering to a surface.

[Prior Art] Generally, in an IC manufacturing process, a circuit pattern for exposure formed on a substrate such as a reticle or a photomask is transferred onto a wafer surface coated with a resist by a semiconductor printing apparatus (stepper or mask aligner). To manufacture ICs.

At this time, if foreign matter such as dust adheres to the substrate surface, the foreign matter is transferred at the same time, which lowers the yield of IC manufacturing. Therefore, in the IC manufacturing process, it is indispensable to detect foreign substances on the substrate.

FIG. 5 shows a conventional foreign matter inspection apparatus. This device is an example utilizing the property that foreign matter scatters isotropic light. A laser beam from a laser light source 61 is divided into two directions by a half mirror 66 via a vibrating mirror (rotating mirror) 64 and an f-θ lens 65 and upper and lower mirrors 67 and 6.
7 'irradiates the back surface (upper surface) 68a and the pattern surface (lower surface) 68b of the reticle 68 along predetermined scanning lines. At this time, the foreign matter scattered light on the back surface 68a of the reticle 68 is detected by a detection system 69 set so as not to detect directly reflected light or other light. Further, foreign matter scattered light on the upper pellicle surface 70 is similarly detected by the detection system 72. Reticle 68
The foreign matter scattered light on the pattern surface 68b is detected by the detection system 73 provided similarly, and the foreign matter scattered light on the lower pellicle surface 71 is detected by the detection system 74.

These detections are performed by scanning the entire surface with a laser beam by operating the reticle in the direction A.

[Problems to be Solved by the Invention] However, in recent years, with the miniaturization of the minimum line width of resolution in semiconductor manufacturing, an improvement in resolution has been required also in fine particle detection on a reticle surface and a pellicle surface.
To meet the demand, the beam diameter on the reticle must be narrower than before, and the incident NA is inevitably large. In this case, on the pellicle surface, the beam diameter increases conversely. Therefore, a sufficient resolution cannot be obtained on the pellicle surface for simultaneously inspecting the reticle surface and the pellicle surface.

The present invention has been made in view of the above-described drawbacks of the related art, and has as its object to provide, for example, a surface state inspection apparatus that can efficiently scan a plurality of inspection surfaces with high accuracy.

Means for Solving the Problems To achieve the above object, according to the present invention, there is provided an inspection apparatus for inspecting a surface state of an inspection object having a pellicle film mounted on a substrate. Light irradiation means for irradiating
Light detecting means for detecting light emitted from the inspection object to inspect the surface state of the inspection object; light-condensing state adjusting means for changing the light-condensing state of the inspection light beam; and Transfer means for reciprocating, comprising a control means for controlling the operation of the light collecting state adjusting means and the transfer means,
The control unit performs the inspection by adjusting the light condensing position to a different one of the substrate surface and the pellicle film surface when the inspection object is moved forward and backward by the transfer unit.

Embodiment FIG. 1 shows an example of an inspection flow according to the present invention. Second
The figure shows an outline of an apparatus for carrying out the flow. In FIG. 2, 1 is a reticle, the lower surface is a chromium substrate surface (Cr surface), and the upper surface is a blank surface (Bl surface).
2 is an upper pellicle surface (Po surface) and 2 'is a lower pellicle surface (Pu surface). The light beam emitted from the laser light source 12 is spread to a constant light beam through the beam expander 11, and is condensed on the reticle 1 by passing through the rotating mirror 9 and the f-θ lens 8 to be perpendicular to the paper surface. Scan linearly.

The incident beam focus switching unit 10 is a mechanism capable of taking an additional lens for switching the focal position into and out of the optical path,
When the additional lens is not inserted into the optical path, the reticle surface (Cr surface and Bl surface) is in focus. 13, 14, 1
5 and 16 are photodetectors. Reticle surface (Cr surface and Bl
The photodetectors 13 and 15 for detecting the scattered light of the foreign matter from the surface are arranged so as to detect the backscattered light with respect to the incident beam. Photodetectors 14 and 16 for detecting scattered light from a pellicle surface (Po and Pu surfaces) are arranged to detect forward scattered light with respect to an incident beam.

Reference numeral 3 denotes a reticle stage, where point O is an initial position, which is forward in the direction of A and backward in the direction of B. When at the point O, the reticle 1 is
It can rotate 180 ゜.

The reticle 1 divides the inspection area into two parts (S area and T area) as shown in FIG.
And it is desirable to carry out every T. This is the incident beam
Because the oblique incidence 40 is blocked by the pellicle support frame 30, the reticle is turned 180 ° and then the T area is inspected again after inspecting the S area first.

 The inspection flow of FIG. 1 will be described.

Reticle surface (Cr, Bl surface) or pellicle surface (Po, Pu)
Inspection may be started from either side. In this embodiment, the inspection starts from the reticle surface.

In the forward movement, a half area (S or T) of the Cr and Bl planes is inspected (step 41). Next, the focus position is switched to the pellicle surface (Po, Pu surface) (step 42). At the time of return, the entire pellicle surface is inspected (step 43). Thereafter, the focus position is switched again to the reticle plane (Cr, Bl plane) (step 44). Subsequently, the reticle is turned 180 ° (step 45). Finally, the remaining half of the reticle (T or S)
Is inspected at the time of forward movement (step 46).

Here, there is a difference in required resolution between the reticle surface and the pellicle surface, and the inspection on the pellicle surface does not require as high accuracy as the reticle surface. Therefore, on the pellicle surface, scanning detection is performed with a large beam diameter corresponding to the required resolution, and the reticle feed speed can be increased.

 Next, a second embodiment will be described.

In the first embodiment, the photodetector for detecting scattered light on the pellicle surface is arranged to receive forward scattered light with respect to an incident beam. Therefore, there is no influence of flare light from the pellicle frame at the time of inspection near the pellicle support frame. At the time of pellicle surface inspection, an entire surface inspection can be performed. However, when the light receiving system must be arranged to receive the backscattered light with respect to the incident beam as shown in FIG. 5 due to the space limitation of the device, etc., as shown in FIG. The effects of flare cannot be ignored. In FIG. 6, reference numeral 40 denotes an incident beam, and 50 and 60 denote detectors for receiving forward scattered light and back scattered light, respectively. Therefore,
At the time of pellicle surface inspection, it is necessary to inspect the inspection area by half in the area of T in FIG. FIG. 4 shows an example of the inspection flowchart at that time. 1 / of the reticle surface during forward movement
Inspection 2 is performed (Step 51), and the focus position is switched to the pellicle surface (Step 52).
Is inspected (step 53). The reticle is turned 180 degrees at the point O (step 54). Subsequently, the remaining half of the pellicle surface is inspected during the forward movement (step 55). Next, the focus position is switched to the reticle surface (step 56), and the other half of the reticle surface is inspected at the time of return, and all inspections are completed. (Step 57).

In these embodiments, if the area to be inspected on the reticle surface or pellicle surface is small enough not to be affected by the pellicle support frame, the entire reticle surface is inspected during forward movement, and the entire pellicle surface is inspected during backward movement. The inspection may be completed in one round trip.

[Effects of the Invention] As described above, in the present invention, the inspection is performed both in the forward movement and the backward movement in the reciprocating operation of the inspection object, so that the inspection time can be greatly reduced,
Since the inspection is executed by adjusting the light condensing position on each surface in each case, it is possible to accurately detect each surface in an appropriate light condensing state.

[Brief description of the drawings]

1 is an inspection flowchart according to a first embodiment of the present invention, FIG. 2 is a configuration diagram of an apparatus according to the first embodiment of the present invention, and FIG. 3 is a pellicle support at the time of reticle surface inspection. FIG. 4 is an explanatory diagram of the influence of a frame on an incident beam, FIG. 4 is an inspection flowchart according to a second embodiment of the present invention, FIG. 5 is a configuration diagram of a conventional apparatus, and FIG. It is explanatory drawing of the flare generated by a pellicle support frame. 1: reticle, 2, 2 ': pellicle, 3: reticle stage, 30: pellicle support frame, 40: incident beam.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-219631 (JP, A) JP-A-61-162736 (JP, A) JP-A-3-34306 (JP, A) JP-A-63-19663 167209 (JP, A) JP-A-1-156641 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 21/84-21/90

Claims (5)

(57) [Claims] An inspection apparatus for inspecting a surface state of an inspection object having a pellicle film mounted on a substrate, wherein the light irradiation means irradiates the inspection object with a light beam for inspection, and inspects a surface state of the inspection object. Light detecting means for detecting light emitted from the object to be inspected, light condensing state adjusting means for changing the light condensing state of the inspection light beam, transfer means for reciprocating the object to be inspected, A light condition adjusting means; and a control means for controlling the operation of the transfer means, wherein the control means controls the substrate surface and the pellicle film at the time of forward and backward movements of the inspection object by the transfer means. A surface state inspection apparatus, wherein inspection is performed by adjusting light condensing positions to different ones of the surfaces. 2. A surface condition inspection apparatus according to claim 1, further comprising means for reversing the object to be inspected with respect to the direction of the reciprocating movement. 3. The apparatus according to claim 1, wherein said control means is configured to change a transfer speed of said transfer means in accordance with an inspection accuracy of an inspection surface of said inspection object. Surface condition inspection device. 4. The object to be inspected comprises a pattern exposure reticle provided with pellicle films on both upper and lower surfaces, and upper and lower surfaces of the pellicle film and upper and lower surfaces of the reticle are inspected surfaces. 2. The surface state inspection apparatus according to claim 1, wherein: 5. A surface condition according to claim 4, wherein said light irradiation means simultaneously irradiates light from upper and lower directions of a pattern exposure reticle provided with a pellicle film on both upper and lower surfaces. Inspection equipment.