Measure the device of wafer film thickness
Technical field
The present invention relates to a kind of measuring equipment, specifically, relate to the device that measures wafer film thickness
Background technology
In manufacture of semiconductor, the device that measures wafer upper film thickness generally includes light source provides incident light, and incident light shines the surface of wafer by optical element, in the surface reflection of wafer.Also be provided with an analytical equipment in the measuring equipment, preserve the light intensity of incident light in this analytical equipment, and can gather reverberation, the light intensity of more catoptrical then light intensity and incident light, thereby the thickness of judgement wafer upper film from crystal column surface.
This shows, the light intensity of incident light is a judgment standard, yet, in the actual use, optical element probably is subjected to the pollution of some acidity or alkaline gas in long-term use, the incident light light intensity will be variant with original incident light light intensity of estimating by the optical element that is polluted, thereby cause the inaccuracy of measurement.
Summary of the invention
The object of the present invention is to provide a kind of device of improved measurement wafer film thickness, it can more accurately measure the film thickness of crystal column surface.
For achieving the above object, the invention provides a kind of device that measures wafer film thickness, this device comprises light source, and optical element and analytical equipment, light source emit beam and be radiated on the wafer by optical element; Wherein, this device also comprises filter and a box, and this filter, light source and optical element place in the described box, and filter is used to filter acid gas and the alkali gas in the box.
Described box also is provided with a breach, and the light that light source sends shines on the wafer by this breach then by optical element, and this breach passes through light uninterruptedly.
The air outlet of described filter is connected with the box outside, and air inlet is located at cassette interior.
The filtering material of described filter mainly is active carbon and polymerizable compound.
Box is that irony and other are difficult for by the material of acid gas and alkali gas corrosion.
Compared with prior art, device of the present invention additionally is provided with a filter, also with filter, light source and optical element place in the box, filter can all be filled into the box outside with the dusty gas in the box, effectively avoided optical element to be polluted, the light intensity that prevents incident light is owing to the variation that can not estimate takes place in the pollution of acid gas and alkali gas, thereby causes the final analysis result precision of analytical equipment to descend.
Description of drawings
To the description of one embodiment of the invention, can further understand purpose, specific structural features and the advantage of its invention by following in conjunction with its accompanying drawing.Wherein, accompanying drawing is:
Fig. 1 measures the work schematic diagram of the device of wafer film thickness for the present invention.
Embodiment
The device that the present invention measures wafer film thickness can measure the thickness of crystal column surface film.
See also Fig. 1, wafer 9 is placed in this device and measures.This device comprises light source 1, optical element 3, filter 5, analytical equipment 7 and box 10.Wherein, light source 1, optical element 3 and filter 5 are concentrated and are inserted in the box 10.Box 10 is provided with a breach, is used to guarantee that the light by optical element 3 can be mapped to wafer 9 uninterruptedly.The air outlet of filter 5 is connected with box 10 outsides, and air inlet is located at box 10 inside, and it can filter box 10 interior gases and discharge box 10 outsides.
In embodiments of the present invention, box 10 can be irony or other are difficult for by the material of acid gas or alkali gas corrosion.Analytical equipment 7 can be preserved the light intensity of incident light in advance.
In the measurement process, light source 1 produces incident light, and incident light shines wafer 9 surfaces by the effect of optical element 3, and this light directly reflexes to analytical equipment 7 on the surface of wafer 9.Analytical equipment 7 collects its light intensity of reverberation post analysis, and the light intensity of catoptrical light intensity with the incident light of preserving in advance compared, and calculates the thickness of wafer 9 surperficial upper films according to intensity variations.
In actual use, the filtering material of filter 5 mainly is active carbon and polymerizable compound.These materials can be filtered acid gas and alkali gas, so filter 5 can effectively filter some acid gas and alkali gas in the box 10, thereby the light intensity that prevents incident light is owing to the variation that can not estimate takes place in the pollution of acid gas and alkali gas, and then has influence on the precision of analytical equipment 7 analysis results.