JP2006023263A

JP2006023263A - Simultaneous measurement of parallelism and flatness by oblique incidence interference measurement

Info

Publication number: JP2006023263A
Application number: JP2004224971A
Authority: JP
Inventors: Tadashi Mizojiri; 唯溝尻
Original assignee: MIZOJIRI OPTICAL CO Ltd
Current assignee: MIZOJIRI OPTICAL CO Ltd
Priority date: 2004-07-05
Filing date: 2004-07-05
Publication date: 2006-01-26

Abstract

<P>PROBLEM TO BE SOLVED: To improve a contrast of an interference fringe on a rough face, and measuring efficiency therein. <P>SOLUTION: Interferometers are installed on both faces to measure a parallelism and a flatness on obverse and reverse faces of an opaque sample concurrently, and an incident angle into the sample is widened using a prism. In a calculation method for the parallelism and the flatness, the sample is moved by a fixed distance along a direction perpendicular to a bottom face of the prism, a change of the interference fringe is image-processed, and calculation is carried out as to the respective obverse and reverse faces, by a phase shift method. The present invention is able to cope with the opaque samples having various sizes and the surface roughness, and is able to shorten a measuring time by the simultaneous measurement for the obverse and reverse faces. The contrast of the interference fringe on the rough face is improved by inclination incidence, and the parallelism and the flatness of the opaque sample having the coarse face are measured concurrently in a second unit of time, by providing the inclination incidence interferometers respectively on the obverse and reverse faces. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、不透明な粗面試料の平行度及び平面度測定を同時にすばやく行うための斜入射干渉計装置である。 The present invention is an oblique incidence interferometer device for quickly and simultaneously measuring parallelism and flatness of an opaque rough surface sample.

従来の斜入射干渉計には、平面度測定のためにプリズムを配置したものがある（例えば、特許文献１参照。）。また不透明体表裏面の平行度測定について述べられたものがある（例えば、特許文献２参照。）。
特開平１−６５４０６号公報（第５頁、第５図）特開平１−１４３９０６号公報 Some conventional oblique incidence interferometers have prisms arranged for flatness measurement (see, for example, Patent Document 1). In addition, there is a description about the parallelism measurement of the front and back surfaces of the opaque body (for example, see Patent Document 2).
JP-A-1-65406 (page 5, FIG. 5) JP-A-1-143906

試料の平行度及び平面度を測定するために、従来は、垂直入射を用いていた。垂直入射だと、粗面における干渉縞のコントラストが悪い。また、不透明な試料の場合、平行度の測定において、表と裏を個別に行うか、垂直入射で行っていた。従って、測定効率が悪かったのを改善しようとするものである。 Conventionally, normal incidence was used to measure the parallelism and flatness of the sample. With normal incidence, the contrast of interference fringes on the rough surface is poor. In the case of an opaque sample, the parallelism is measured separately for the front and back sides or at normal incidence. Therefore, it is intended to improve the poor measurement efficiency.

Means for Solving the Problems and Effects of the Invention

本発明の最大の利点は、様々なサイズや表面粗さを持つ不透明な試料に対応可能ということと、表裏面同時計測による測定時間の短縮ができたことである。斜入射にすることで粗面における干渉縞のコントラストを良くし、かつ、斜入射干渉計を表裏それぞれに設置することで、不透明な粗面試料の平行度及び平面度測定を同時に秒単位で行うようにするものである。また、試料の表側と裏側の干渉計を別々にすることで、様々な厚みの試料に対応でき、大きな試料に対しては、試料を動かすスペースを自由にとれるので、試料を動かすことで対応できるようにするものである。 The greatest advantage of the present invention is that it is possible to deal with opaque samples having various sizes and surface roughness, and that the measurement time can be shortened by simultaneous measurement of the front and back surfaces. Increasing the contrast of interference fringes on the rough surface by using oblique incidence, and installing oblique incidence interferometers on the front and back sides, the parallelism and flatness measurement of opaque rough surface samples can be simultaneously performed in seconds. It is what you want to do. In addition, by separating the interferometers on the front and back sides of the sample, it is possible to handle samples of various thicknesses, and for large samples, the space for moving the sample can be taken freely, so it can be handled by moving the sample. It is what you want to do.

予想される表面粗さの最大値から試料への入射角を決め、干渉縞のコントラストを定める。それに応じてプリズム等の光学素子を配置し図１のように２つの干渉計を用意する。試料の位置にオプチカルフラットを配置し、２つの干渉計内のプリズムの底面が平行になるようにする。このとき、試料の厚みにあわせて２つのプリズムの底面間の距離を試料の厚みより０．２〜０．３ｍｍ程度厚く設置する。試料とプリズムの底面の距離を短くすることでプリズムを小型化でき、省スペースかつ経済的である。 The incident angle to the sample is determined from the maximum value of the expected surface roughness, and the contrast of the interference fringes is determined. Accordingly, optical elements such as prisms are arranged, and two interferometers are prepared as shown in FIG. An optical flat is arranged at the position of the sample so that the bottom surfaces of the prisms in the two interferometers are parallel. At this time, the distance between the bottom surfaces of the two prisms is set to be about 0.2 to 0.3 mm thicker than the thickness of the sample in accordance with the thickness of the sample. By shortening the distance between the sample and the bottom surface of the prism, the prism can be miniaturized, saving space and being economical.

本発明の不透明な粗面試料の斜入射干渉測定による平行度、平面度の同時測定を実施するための最良の形態の正面図である。It is a front view of the best mode for carrying out simultaneous measurement of parallelism and flatness by oblique incidence interference measurement of an opaque rough surface sample of the present invention.

Explanation of symbols

１カメラ１
２スクリーン１
３スクリーン２
４カメラ２
５プリズム１
６プリズム２
７光源部１
８光源部２1 Camera 1
2 Screen 1
3 Screen 2
4 Camera 2
5 Prism 1
6 Prism 2
7 Light source 1
8 Light source 2

Claims

Light beams from the coherent light source unit 1 and the light source unit 2 are obliquely incident on an opaque sample. A prism 1 and a prism 2 are arranged on the incident optical path to the sample and the reflected optical path from the sample as shown in FIG. At this time, the bottom surfaces of the prism 1 and the prism 2 and the front and back surfaces of the sample (surfaces facing the prism 1 and the prism 2) are made approximately parallel. The reflected light coming out of the prism is projected on the screen 1 and the screen 2 installed in parallel with the front and back surfaces of the sample, and this is photographed by the camera 1 and the camera 2. Interference fringes of reflected light from the front and back surfaces of the sample and the bottom surfaces of the prisms 1 and 2 are photographed with a camera, and image analysis is performed to measure the parallelism and flatness of the front and back surfaces of the sample. This is a measurement interferometer.
An object of the present invention is to measure the parallelism and flatness of the front and back surfaces of a sample having an opaque rough surface in a short time without contact. If it is only necessary to measure the parallelism of the front and back surfaces of an opaque sample, it may be performed as in Patent Document 2 described in the specification, but at the same time, interferometers are installed on both sides in order to measure flatness, and coarse The incidence angle on the sample was increased in order to enable measurement of the surface. Simply increasing the angle of incidence makes the device very large with respect to the sample. Since it is known that the apparatus can be miniaturized by installing a prism instead of the optical flat, the prism is installed in the present invention.
As a calculation method of parallelism and flatness, the sample is rotated eight times in a direction perpendicular to the bottom surface of the prism, for example, eight times, a change in interference fringes is image-processed, and the front and back surfaces are calculated by the phase shift method.