JP2536055B2 - Development monitoring method - Google Patents

Description

The present invention relates to a development monitoring method, and more particularly to a development monitoring method for monitoring the progress of development of an optical disc master.

[Prior Art] A conventional development monitoring method will be described in detail with reference to the drawings.

In the development monitor apparatus shown in FIG. 3, the laser beam a is applied to the pattern surface of the optical disc master which is fixed to the chuck table 2 and is being developed while being rotated by the spindle 3.
The 0th-order diffracted light b and the 1st-order diffracted light c obtained by irradiating are detected by a pair of detectors 4 and 5.

The voltage signals d and e of the detectors 4 and 5 are amplified by the pair of amplifiers 7 and 8 to be the 0th-order diffracted light intensity signal f and the 1st-order diffracted light intensity signal g.
Becomes

The diffracted light ratio monitor unit calculates the diffracted light ratio g / f from the 0th-order diffracted light intensity signal f and the 1st-order diffracted light intensity signal g and outputs it to the terminal 200 as the diffracted light ratio signal h.

When the diffracted light ratio signal h output to the terminal 200 reaches a desired diffracted light ratio, the dropping of the developing solution is stopped and the development is completed. Further, it is known that the diffracted light ratio and the groove width are in a proportional relationship, so that the group width at the monitor position can be made constant.

However, in actual exposure, a difference occurs in the exposure amount per unit area in the radial direction of the pattern, so that a difference occurs in the group width other than the monitor radius.

[Problems to be Solved by the Invention]

However, the above-described conventional development monitoring method as described above can be obtained as the development progresses by irradiating the optical disc master with a laser beam at one point in the radial direction.
Since the light intensity of the second-order diffracted light and the first-order diffracted light is detected by using a pair of detector and amplifier, the exposure amount per unit area changes in the pattern radial direction on the optical disc master, and the diffracted light ratio is increased. Even if the signal changes, there is a drawback that the diffracted light ratio signal in the radial direction of the pattern cannot be monitored.

[Means for solving the problem]

The development monitoring method of the present invention irradiates while sequentially scanning the laser beam in the radial direction on the pattern surface of the rotating optical disk master, so that the 0th-order diffracted light and the 1st-order diffraction light obtained from the pattern surface are obtained as the development progresses. The folding light was sequentially sampled by a pair of detectors that scan in coincidence with the scanning of the laser beam, and the diffracted light ratio was sequentially calculated from the 0th-order diffracted light intensity and the 1st-order diffracted light intensity detected and obtained. It is configured to monitor the development progress in the radial direction of the pattern from the diffracted light ratio signal.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

In the development monitor apparatus shown in FIG. 1, an optical disk master 1 is fixed to a chuck table 2 and rotated by a spindle 3. The laser beam is sequentially scanned (indicated by an arrow) in the radial direction of the optical disc master 1 to produce a laser beam.
The pattern surface of the optical disc master 1 is irradiated with a ₁ , a ₂ , a ₃ , ..., A _n .

The 0th-order diffracted light b is detected by the detector 4 as the 1st-order diffracted light c.
Are respectively detected by the detector 5. The detector 4 and the detector 5 are sequentially scanned by the radius method of the optical disc master 1 in accordance with the scanning of the laser beam from the moving stage 6.

Therefore, the 0th-order diffracted lights b ₁ , b ₂ , b ₃ , ..., b _n are output as voltage signals d ₁ , d ₂ , d ₃ , ..., d _n detected by the detector 4, and the 1st-order diffracted light c _{1 , c 2, c 3, ~} , c n are voltage signals e ₁ detected by the detector _{5, e 2, e 3, ~} , it is output as e _n.

The amplifier 7 amplifies the voltage signals d ₁ , d ₂ , d ₃ , ..., d _n and outputs them as 0th-order diffracted light intensity signals f ₁ , f ₂ , f ₃ , ..., f _n , and the amplifier 8 outputs the voltage signal e _{1 , e 2, e 3, ~} , amplifies the e _n 1-order diffracted light intensity signal
Output as g ₁ , g ₂ , g ₃ , ..., g _n .

The diffracted light ratio monitor unit 9 controls the 0th-order diffracted light intensity signals f ₁ , f ₂ , f ₃ ,
~, F _n the first-order diffracted light intensity signals _{g 1, g 2, g 3} , ~, g n diffractive optical ratio signal by calculating the diffraction light ratio and a _{h 1, h 2, h 3} , ~, as h _n Terminal
Output to 200.

FIG. 2 is a graph showing the relationship between the diffracted light ratio signal output from the diffracted light ratio monitor unit shown in FIG. 1 and the pattern radius of the optical disc master, and from the inner circumference γ ₂ to the outer circumference γ ₃ in the radial direction. If the exposure amount per unit area is constant,
The diffracted light ratio signal h of the inner circumference γ ₂ , the middle circumference γ ₁ , and the outer circumference γ ₃ becomes constant and becomes h ₁ at each position and becomes a straight line 20, but the exposure amount of the inner circumference γ ₁ is larger than that of the outer circumference γ _3. When it is small, it becomes a straight line 21,
When the exposure amount of the inner circumference γ ₁ is larger than the exposure amount of the outer circumference γ ₃ , the straight line 22 is obtained.

Therefore, the diffracted light ratio signal in the radial direction of the pattern is detected by using the development monitoring method of the present invention. By moving to the outer circumference and suppressing the development signal on the inner circumference of the pattern, or when the diffracted light ratio signal on the inner circumference of the pattern is smaller than the diffracted light ratio signal on the outer circumference, for example, pure water is dropped on the outer circumference to drop the pattern outer circumference. By suppressing the progress of development, it is possible to create a uniform group width on the inner and outer circumferences of the pattern.

〔The invention's effect〕

According to the development monitoring method of the present invention, the laser beam is sequentially scanned in the same radial direction on the pattern surface of the optical disc master, and the diffracted light ratio is sequentially detected from the 0th-order diffracted light and the 1st-order diffracted light that are obtained. When the amount of exposure per unit area changes in the pattern radial direction, the change in the diffracted light ratio signal in the radial direction of the pattern can be monitored.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a graph showing the relationship between the diffracted light ratio signal and the pattern radius in the embodiment shown in FIG. 1, and FIG. 3 is a conventional example. It is a block diagram. 1 ... Optical disc master, 2 ... Chuck table, 3 ...
… Spindle, 4,5 …… Detector, 6 …… Movement stage,
7,8 ... Amplifier, 9 ... Diffraction ratio monitor, 20,21,22 ...
… Straight line, a, a ₁ , a ₂ , a ₃ , 〜, a _n , ... laser beam, b ……
0th-order diffracted light, c ... 1st-order diffracted light, d, e ... voltage signal, f
...... 0th order diffracted light intensity signal, g ...... 1st order diffracted light intensity signal,
h, h ₁ ...... Diffraction light ratio signal, γ, γ ₁ , γ ₂ , γ ₃ ...... Radius.

Claims (1)

(57) [Claims] 1. A laser beam is irradiated while being sequentially scanned in a radial direction on a pattern surface of a rotating optical disk master, and the 0th-order diffracted light and the 1st-order diffracted light obtained from the pattern surface are developed as the development progresses. Sampling is sequentially performed by a pair of detectors that scan in accordance with the scanning of the beam, and the diffracted light ratio is sequentially calculated from the detected 0th-order diffracted light intensity and the 1st-order diffracted light intensity, and the pattern radius is obtained from the obtained diffracted light ratio signal. A development monitoring method, characterized in that the development progress in a direction is monitored.