JPH062697U - Standard chip mounting base with variable tilt angle - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a mounting base with a variable tilt angle for a reference chip for focus adjustment of an inspection optical system of an IC chip. [Structure] Has a double structure of a sample table 41 and a fixed table 42,
Circular suction holes 411 for the reference chip 1 are provided on the sample table 41, and four adjusting bolts 412a for elastically fixing the four corners of the sample table 41 to the fixed table 42 via disc springs 413, respectively.
... is provided. Further, the sample table 41 is eccentrically and rotatably supported with respect to the fixed table 42, is interposed at an appropriate position between the sample table 41 and the fixed table 42, and the handle 51 is operated to move the sample table 41 relative to the fixed table 42. It is configured by providing a metal ball 52 whose tilt angle can be changed. [Effect] The reference pattern is accurately focused on the inspection optical system.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a structure of a mounting base having a variable tilt angle, which mounts a reference chip for an inspection optical system of an IC chip.

[0002]

[Prior art]

 The wiring pattern of the semiconductor IC chip formed on the wafer is inspected by the pattern inspection device. In the optical system of the pattern inspection apparatus, the focus and the like are adjusted beforehand by the reference chip having the reference pattern, and the reference chip mounting base is used for this adjustment.

An outline of a conventional reference chip mounting base and a focus adjusting method for an inspection optical system using the same will be described with reference to FIG. In the figure, the reference chip 1 on which the reference pattern 11 is formed is mounted on the mounting base 2, and air is adsorbed by a circular adsorption hole 21 provided in the center of the mounting base 2. The objective lens 31 of the inspection optical system 3 approaches the adsorbed reference chip 1 at a minute distance to receive the reference pattern 11, and the focus is adjusted so as to be clear. In the above, since the objective lens 31 has a very shallow depth of focus and the reference pattern has a narrow width of submicron, the minute distance to the reference chip 1 is adjusted with high accuracy of 0.1 μm. On the other hand, the reference chip 1 needs to be correctly mounted horizontally on the mounting table 2. This is because the reference pattern 11 is partially or totally defocused when it is not horizontal.

[0004]

[Problems to be solved by the device]

 Since the air suction to the reference chip 1 is performed by the circular suction holes 21, the entire surface is not uniformly sucked and is bent or distorted regardless of the degree. FIG. 2 (b) shows an example of the distorted reference chip 1. The vicinity of the suction hole 21 is in close contact with the surface of the mounting table 2, but when it is separated from it, it is slightly raised. When the amount of uplift is large, it reaches several μm or more and causes defocusing. In order to prevent such defocusing, it is basically desirable to improve the suction method, but as the second best measure, the method of making the tilt angle of the mounting table 2 variable is effective. It has been confirmed that the defocusing of the inspection optical system can be adjusted to such an extent that there is no practical problem. The present invention has been made in view of the above, and an object thereof is to provide a reference chip mounting base with a variable tilt angle.

[0005]

[Means for Solving the Problems]

 This invention is a reference chip mounting base with a variable tilt angle, and has a double structure of a sample base and a fixed base. A circular suction hole for the reference chip is provided on the sample table, and four adjusting bolts for elastically fixing the four corners of the sample table to the fixed table via disc springs are provided. Furthermore, it is eccentric to the fixed table and is rotatably supported, and is interposed at an appropriate position between the sample table and the fixed table. By operating the handle, the inclination angle of the sample table with respect to the fixed table can be changed. It is composed of metal balls.

[0006]

[Action]

 In the reference chip mounting base having the above-mentioned double structure, the reference chip is air-adsorbed by the circular adsorption holes provided in the upper sample base. The four corners of the sample table are elastically fixed to the fixed table by four adjusting bolts via disc springs, respectively. On the other hand, when the metal sphere is operated by the handle, the metal sphere is eccentric with respect to the fixed base, so that the sample base moves upward or downward and the inclination angle changes. When the focus cannot be adjusted properly due to the distortion of the reference chip, the focus can be adjusted correctly by changing the tilt angle of the sample table by the hand operation.

[0007]

【Example】

 1A and 1B show an embodiment of the present invention. FIG. 1A is a plan view of a reference chip mounting base with a variable tilt angle, and FIG. 1B is a vertical sectional view taken along line AA of FIG. In (a) and (b), the reference chip mounting base 4 is composed of an upper sample base 41 and a lower fixed base 42. The sample table 41 is provided with a circular suction hole 411 similar to the conventional one for the reference chip 1. The four corners of the sample table 41 are elastically fixed to the fixed table 42 by four adjusting bolts 412a to 412d via disc springs 413. An operation mechanism 5 including a handle 51 and a metal ball 52 is provided, the metal ball 52 is eccentrically supported with respect to the fixed base 42, and is rotatably supported. Further, a fixing screw 43 for fixing the sample table 41 to the fixing table 42 is provided.

The method of using the mounting table 4 will be described. First, when the sample table 41 is elastically fixed to the fixing table 42 by the adjusting bolts 412a and the like, the metal ball 52 is pressed by both to stabilize. . In this condition, the focus of the inspection optical system 3 is adjusted. If the reference chip 1 is distorted and the focus cannot be adjusted correctly, refer to the adjustment data and move the handle 51 up or down as indicated by the arrow. If the tilt angle is changed appropriately by operating left and right, there is a point that the surface of the reference chip 1 becomes correctly horizontal with respect to the objective lens 31 (see Fig. 1 (b)). The base 41 is fixed to the fixed base 42. As described above, accurate focus adjustment can be performed on the reference pattern 11.

[0009]

[Effect of device]

 As explained above, in the reference chip mounting table according to the present invention, when the mounted reference chip is distorted by air suction, the tilt angle of the sample table is changed to change the reference chip for the inspection optical system. The pattern is precisely focused and contributes to improving the efficiency of wafer pattern inspection.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a plan view of a reference chip mounting base with variable tilt angle, and (b) is a vertical sectional view taken along the line AA of (a).

FIG. 2A is an explanatory view of an outline of a conventional reference chip mounting base and a focus adjusting method of an inspection optical system using the same, and FIG. 2B is a diagram showing an example of a distorted reference chip 1.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reference chip, 11 ... Reference pattern, 2 ... Conventional reference chip mounting base, 21 ... Adsorption hole, 3 ... Inspection optical system, 31 ... Objective lens, 4 ... Reference chip mounting base of this invention, 41 ... Sample base,
411… Suction hole, 412a, 412b, 412c, 412d… Adjustment bolt, 41
3 ... Disc spring, 42 ... Fixing base, 43 ... Fixing screw 5 ... Operating mechanism, 51 ... Handle, 52 ... Metal ball.

Claims (1)

[Scope of utility model registration request] 1. A reference chip having a reference pattern is mounted on an inspection optical system for inspecting a pattern of an IC chip formed on a wafer, air is adsorbed by a circular adsorption hole, and the reference is provided by the inspection optical system. A reference chip mounting base for receiving a pattern to perform focus adjustment has a double structure of a sample base and a fixed base, and the sample base has a circular suction hole for the reference chip and the fixed base for the fixed base. Sample table 4
Between the sample base and the fixed base, the corners are provided with four adjusting bolts for elastically fixing them via disc springs, respectively, are eccentric to the fixed base, and are rotatably supported. A reference chip mounting base with a variable tilt angle, characterized in that it is provided with a metal ball that is interposed at an appropriate position and is capable of changing the tilt angle of the sample base with respect to the fixed base by operating the handle.