CN209706766U - Inverse Hartmann's optical path wafer surface roughness measuring device - Google Patents

Abstract

The utility model relates to inverse Hartmann's optical path wafer surface roughness measuring devices.LCD display in the utility model is fixed on bottom of device, total reflection mirror and spectroscope are fixed at sustained height, and it is located at the surface of LCD display and tested wafer, LCD display shows that the stripe pattern encoded through light intensity, the Image Acquisition of preposition aperture CMOS camera are controlled by computer, and image procossing and error compensation are realized by computer.

Description

Inverse Hartmann Optical Path Wafer Surface Roughness Measuring Device

technical field

The utility model belongs to the technical field of measurement and relates to a wafer surface roughness measuring device based on an inverse Hartmann optical path. It is mainly used for the measurement of wafer surface roughness.

Background technique

With the rapid development of information technology, the demand for semiconductor components continues to increase, and higher requirements are placed on the types and functions of semiconductor components. As the raw material for manufacturing semiconductor integrated circuits, the surface roughness of wafer directly affects the quality of semiconductor products.

The existing wafer surface roughness measurement methods all have the problem of complex devices, and the mechanical probe method is easy to damage the surface to be measured; the microscope method and laser interferometry are expensive. Therefore, it is very important to make up for the defects of these wafer surface roughness measurement devices.

Contents of the invention

Aiming at the deficiencies of the prior art, the utility model proposes a measuring device with high precision, low cost and simple device structure.

The utility model comprises an LCD display screen, a total reflection mirror, a beam splitter, a microlens, a front small hole CMOS camera and a computer.

The LCD display screen displays light and dark stripes coded by light intensity.

The fringe light beam projected by the LCD display screen is reflected by the total reflection mirror and then projected to the beam splitter.

The beam splitter reflects the streaked light beam and projects it to the microlens.

The microlens condenses the fringe beams and projects them onto the surface of the wafer to be tested.

The front pinhole CMOS camera receives the streaked light beam reflected by the wafer surface.

The computer controls the LCD display screen and the front small hole CMOS camera, and realizes the high-precision measurement function through image acquisition, image processing and error compensation.

The beneficial effects of the utility model are:

1. The small hole in the front of the CMOS camera can filter out stray light, avoiding the interference of external light on the CMOS camera.

2. Through the error compensation system, the influence of system errors on the measurement results can be eliminated and the measurement accuracy can be improved.

Description of drawings

Fig. 1 is a schematic diagram of the optical path of the device of the present invention.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is further described.

As shown in Figure 1, the optical path of the measurement device in this embodiment consists of an LCD display 1, a total reflection mirror 2, a beam splitter 3, a microlens 4, a wafer to be measured 5, a front small hole CMOS camera 6, and a computer 7. .

Working process of the present utility model:

In the work of wafer surface roughness measurement, the inverse Hartmann optical path is used. In the inverse Hartmann optical path, the spot coordinates of the points on the wafer surface projected on the front pinhole CMOS camera are measured, and the ideal spot coordinates of the corresponding positions are obtained through the optical path tracing model. Finally, a comparative calculation is performed to obtain the surface roughness of the wafer.

The measurement steps are as follows:

1. The LCD screen is controlled by a computer to generate bright and dark stripes coded by light intensity, and the light path of the stripe light changes after being reflected by the total reflection mirror;

2. The reflected streak light changes the light path again after being reflected by the beam splitter, and is projected into the microlens and enlarged.

3. The enlarged streak light is deformed after being reflected by the surface of the wafer under test, and is received by the front small hole CMOS camera.

4. According to the ray tracing model, the ideal spot coordinate value of the corresponding position is obtained.

5. Compare the actual spot coordinates with the ideal spot coordinates, and calculate the surface roughness of the tested wafer surface.

Claims (2)

1. against Hartmann's optical path wafer surface roughness measuring device, including it is LCD display, total reflection mirror, spectroscope, micro- Mirror, preposition aperture CMOS camera and computer, it is characterised in that:

The LCD display shows the light and shade striped encoded through light intensity,

It is projected after the striped light beam of the total reflection mirror reflective LCD display screen projection to spectroscope,

It is projected after the spectroscope reflection strip light beam to microlens,

The microlens is projected to tested crystal column surface after assembling striped light beam,

The preposition aperture CMOS camera receives the striped light beam after being reflected by crystal column surface,

The computer control LCD display and preposition aperture CMOS camera, are mended by Image Acquisition, image procossing and error It repays, realizes high-acruracy survey function.

2. inverse Hartmann's optical path wafer surface roughness measuring device according to claim 1, it is characterised in that:

Wafer surface roughness optical path uses inverse Hartmann's optical path,

Computer uses error compensation system, realizes high-acruracy survey.