Method of measuring substrate surface purity

FIELD: physics.

SUBSTANCE: method involves depositing a droplet of liquid on the surface of the analysed substrate. Further, the droplet is illuminated with light with uniformly distributed intensity on the section of the light flux. Intensity of the light flux is then determined using a photodetector matrix, which is used to determine drop spreading parametres of the liquid. Purity of the surface of the substrate is determined by comparing the obtained parametres with standard parametres. The parametre used for controlling degree of purity is length of the wetting channel and its width given the inequality 16°<α<56°, where α is angle of inclination of the surface of the substrate to the horizontal, is satisfied. A standard curve of drop spreading parametres of the liquid versus substrate surface purity is plotted from which numerical value of surface purity is determined through application of numerical values of width and length of the wetting channel onto the said curve.

EFFECT: increased accuracy of measuring substrate surface purity and increased efficiency.

6 dwg

 

The invention relates to the field of measurement technology and can be used in microelectronics in the manufacture of integrated circuits on the active and passive substrates and diffractive optics in the production of diffractive optical elements.

The known method (A.S. USSR №1260752, CL G01N 13/02, 1982) to determine the purity of the surface of the substrate on the value of the wetting angle by measuring the volume of a drop placed on a flat substrate. However, this method of determining surface cleanliness is very time consuming, because you first need to measure the geometrical parameters of the drops and then determines the target value of the angle that determines the purity of the surface of the substrate.

The known method (A.S. USSR №1821688, CL G01N 13/02, 1993) to determine the purity of the surface of the substrate on the velocity of the sliding counterface on the surface of the investigated substrate, which consists in the fact that the test substrate is placed relative to another, identical studied, at an angle of 5-10° between their planes with the touch point. Under the action of gravity one of them is the sliding counterface on the substrate and the velocity of sliding is judged on the cleanliness of the substrate surface.

The disadvantages of this method are the need for precise control of the angle of inclination of the substrate, through which implemented aetsa slide movable substrate (counterface). High sensitivity to the change in the value of this angle leads to a significant breach of the accuracy of the measurement of the purity of the surface of the substrate, to eliminate the measurement process include an additional control device for the deviation angle of the slide from the setpoint. This requirement greatly reduces the performance of the method, adds cost and complexity to the measurement process.

The closest in technical essence to the present invention is a method (AS the USSR №17848668, CL G01N 13/02, 1992) to determine the purity of the surface of the substrate on the rate of spreading of a liquid drop on a flat surface, which consists in the fact that on the surface of the investigated substrate is applied a drop of fluid, light it light with a uniform intensity distribution over the cross section of the light flux, fix the value of the intensity of the light flux photodetector matrix, the rate of change of the intensity values of the light flux determine the numerical value of the speed of spreading of a liquid drop, which is applied on reference dependence to determine the purity of the substrate surface.

However, this method of determining the purity of the surface provides the drops fall from some height, which leads to the oscillatory motion of the droplets, and hence the light on the eye, what complicates the process of analyzing the functional dependence of surface roughness on the rate of drop spreading. Another disadvantage of this method is the inability of the Desk surface with inhomogeneous distribution of impurities, which generates different values of the speed of spreading in different directions, and the measurement values of the surface of the substrate becomes difficult. These shortcomings lead to a decrease in accuracy, complexity and cost of the measurement process.

The basis of the invention is the task of increasing productivity and accuracy of the measurement of surface roughness of the substrate.

This problem is solved due to the fact that in the method of measuring the purity of the surface of the substrate to produce a coating liquid droplets on the analyzed surface, inclined at an angle α, illuminate its light with a uniform intensity distribution over the cross section of the light flux, record the intensity of light photodetector matrix, and as a controlled parameter using the length and width of the channel wettability provided the inequality 16°<α<56°, build the reference dependence of the length and the channel width of the wetting liquid droplets from the surface of the substrate, applying at which the numerical values of the length and width of the channel smachine the barb determine the numerical value of the purity of the substrate surface.

Figure 1 shows the layout of a substrate inclined at an angle α, applied to its surface a drop of liquid, the illuminated light flux with a uniform intensity distribution in its cross-section, and photodetecting devices, figure 2 depicts the moment of contact of a drop of liquid with the surface, i.e. the beginning of the process measurement of surface roughness of the investigated substrates, figure 3 presents the appearance of a drop of liquid spilled on technologically clean surface of a horizontal substrate, figure 4 shows the shape of the trace drops of liquid remaining after draining technologically clean surface, figure 5 - the trail drops of liquid flowing through the contaminated surface.

In the starting position to produce a coating liquid droplets on the surface of the investigated substrate inclined at an angle α, illuminate its light with a uniform intensity distribution over the cross section of the light flux, record the intensity of light of a one-dimensional matrix (figure 1). Photodetector sees luminous flux in this position for zero - the beginning of the movement of the drop (figure 2).

If you measure the dimensions of the field of wetting of the surface being investigated for horizontal substrate, are formed wetting irregular shape is defined by neodnorodno the distributed residual contamination. This substantially complicates the measurement of its geometric dimensions (figure 3).

In the interaction of the liquid droplets of the inclined surface of the investigated substrate occurs opposition forces wettability and accelerated motion of drops on the surface. This mechanism narrows the scope of the interaction of the droplets with the surface of the substrate, substantially reducing the impact on the process of drop spreading heterogeneously distributed contamination remaining, for example, after finishing cleaning fluids adsorbed by the surface of the substrate during its storage, etc. This leads to the fact that the region of the wettability is obtained the correct form (figure 4) and the D parameter is easily measured by simple and accessible by optical means. Small footprint wettability allows scanning surface, identifying areas of local contamination, i.e. discontinuities.

Using surfaces with a known concentration of impurities, it is possible to construct a gauge parameter dependence of the width and length of the field wettability dripping with the concentration of these impurities, which are always equipped with specific devices. The proposal is used to produce a calibration curve of known standard methods to determine the purity of the surface of the substrate methods of dipping, dew and instrument ICH-2. Ka is irrevoca dependence presented in figure 5.

According to the presented dependence by measuring, for example, a metal ruler or metric scale microscope width and channel length wettability, you can determine the number of contaminants on the surface of the substrate in units of g/cm2.

This process can be automated using software, the availability of Bank computer reference dependence, presented in figure 5, and as a sensor of a charge-coupled device (CCD). In the case of use as photometric CCD, the width or length of the wetting can be measured with accuracy to the size of the CCD element, i.e. with an accuracy of units, tenths of a micron.

The method is as follows.

Let a drop of known mass and volume is applied to the surface of the substrate is inclined at an angle α, and is illuminated by light with a uniform intensity distribution in its cross-section. At the moment of touch a drop of the liquid surface of the investigated substrate is fixed starting point of the process of draining the liquid droplets on inclined surfaces. When performing inequality 16°<α<56° to the substrate surface remains the trail of fallen drops in the form of a liquid film, the geometrical dimensions of which are easily measured, for example, a simple microscope with a lens having on its surface a metric ruler. Measurement the data width and the channel length wettability is applied to the axis of the gauge dependence, 5, corresponding to these values, which determine the numerical values of surface roughness of the substrates in g/cm2.

The decrease in the angle of inclination of the investigated substrate is less than α=16 leads to a significant increase in the area spreading and changing the shape of the footprint of its spreading in the field of primary interaction of the droplets with the surface of the substrate, and the whole channel wettability, because of the longer interaction of liquid drops with the surface of the investigated substrate resulting from low speed draining liquid droplets. This complicates the process of measuring the geometric dimensions of the footprint of the spreading of a liquid drop, consequently, reduces the performance and accuracy of the measurement of surface roughness of the investigated substrates. Particularly this property manifests itself in determining the purity of ultrapure surfaces.

Increasing the angle of inclination of the investigated substrate more than α=56° leads to a significant increase in the rate of spreading. The value of her energy in this case begins to exceed the binding energy of surface atoms of a liquid drop with atoms and molecules of the contaminants and the surface of the substrate, which will eventually cease to influence the process of spreading of a liquid drop on the surface of the investigated substrates.

It is perceived F. toprani device as a droplet of liquid on the dirty surface of the investigated substrate (6).

The method for determining the cleanliness of a surface of the substrate allows to measure the degree of purity super clean surfaces. In this case, to reduce the spreading effect increase the angle of inclination of the investigated substrates. On the other hand, at fixed angle of inclination of the investigated substrate and the mass of liquid droplets increase the spreading effect leads to the reduction of channel length, wetted by the liquid drop due to absorption by the surface of the substrate part of the droplet volume, i.e. the length l of the channel wettability of the surface being investigated also serves as a criterion of purity.

A method of measuring the purity of the surface of the substrate, namely, that make the application of a drop of liquid on the surface of the investigated substrate, cover it with a flood of light with a uniform intensity distribution over the cross section of the light flux, record the intensity of light photodetector matrix, determine the parameter of the spreading of a liquid drop, which is causing the reference dependence judge the cleanliness of a surface of the substrate, characterized in that as the parameter of drop spreading use the channel length wettability and its width under the condition that the inequality 16°<α<56°, where α is the tilt angle of the substrate surface to the horizon, build reference parameter dependence of the spreading liquid droplets from the surface mean the LCD drawing on which the numerical values of the width or length of the channel wettability determine the numerical value of the purity of the surface of the substrate.



 

Same patents:

Flaw detector // 2375702

FIELD: instrument making.

SUBSTANCE: invention relates to detection of surface defects representing material discontinuity. Proposed device comprises electromagnetic wave radiator and reflected signal photo receiver. The former represents laser with low-intensity visible electromagnetic wave range. The latter represents a photodiode. Flaw detector comprises also signal amplifier, comparator to generate "defect" short signal-pulse signal when laser incident beam gets on surface defects, one-shot multivibrator that converts aforesaid pulse into longer pulse sufficient for operator perception, light indicator operated by aforesaid "defect" signal and device to move controlled part. Note that signal generated in photo receiver by radiation reflected from party surface comes into amplifier and, thereafter, into comparator. Now, aforesaid signal comes from comparator to one-shot multivibrator, then, to light indicator and, at a time, to sound generator and, further on, to sound converter. Note here that controlled part is driven so that incident laser beam focus stays on controlled part surface.

EFFECT: expanded performances.

3 dwg

Roughness metre // 2375677

FIELD: physics; optics.

SUBSTANCE: invention relates to devices for measuring surface roughness. The roughness metre has a light emitter and a reflected signal photodetector. The light emitter is a laser and the reflected signal photodetector is a photodiode. The roughness metre also has devices for defocusing the light beam incident on the analysed surface and focusing light reflected by this surface, an amplifier for amplifying signal from the photodiode, comparator, AND circuit, binary pulse counter, pulse decoder, memory storage for standard codes, digital comparison device, display device. The signal from the photodiode is transmitted to the amplifier, from the output of the amplifier to the comparator input, from the comparator output to the AND circuit, then to the input of the binary pulse counter, further to the input of the decode, from the output of the decoder to the input of the digital comparison device where signals from the memory storage for standard codes are also transmitted at the same time, and from the output of the digital comparison device to the input of the display device.

EFFECT: wider operational characteristics of the roughness metre.

2 dwg

FIELD: instrument engineering.

SUBSTANCE: method of defining cavity depth at optical surface of viewing port outer glass of manned space vehicle includes cavity stereo photography, measuring of distance from the centre of each stereo pair picture to the same point of cavity image. Also measurement of distance between lens axes for the first and the second shot, measurement of distance from lens main surface to the surface of viewing port inner glass and measurement of air medium pressure in pressurised section and in space between glasses. Cavity depth is calculated from the expression:

.

EFFECT: accurate definition of cavity (defect) depth of viewing port outer glass in flight conditions with required accuracy.

2 dwg

FIELD: physics, measurement.

SUBSTANCE: invention relates to control instrumentation and can be used for diagnostics of fracture formation and forecasting a residual operating hours of metal structures before formation of macro fractures in strain concentrations zones that are subjected to loading under conditions of cyclic elastoplastic or plastic deformation. The proposed method comprises the steps that follow. The most probable points of metal structure breakage are determined, check sites surfaces are analysed and degree of damage is defined. Note that two or more reference lines are marked on the check sites surface nearby the strain concentrator, in parallel to expected development of the fracture and at equal distance from each other. Now, a number of checks of metal structures under control are consecutively effected, in a present number of cycles consisting in measuring the distance between reference lines and defining the degree of damage from the change of the said distance.

EFFECT: expanded application of fracture formation diagnostics in metal structures with their elements being subjected to plastic or elastoplastic deformation.

6 dwg

FIELD: physics.

SUBSTANCE: fault location and identification device for inaccessible sites behind a wall, accommodates the first endoscope applied for illumination with visible light and observation. Herewith the first endoscope and penetrating agent supply and spraying tubes are arranged together within rod. The rod can be delivered into the wall aperture for observing a product part. Besides, the device includes the second endoscope, independent of the first endoscope and the rod and designed for ultraviolet exposure and observation of area of the part that has been processed by penetrating agents.

EFFECT: improved quality of UV observation.

12 cl, 5 dwg

FIELD: electronics.

SUBSTANCE: invention can be used when making semiconductor devices, liquid crystal displays, photomasks and other products. The control method involves illuminating the controlled object with radiation in the optical range from a point source and analysis of the reflected light image on a special screen. There is successive measurement of the intensity of elements of the image of the given dimension with subsequent calculation of X, Y and Z coordinates of the controlled surface.

EFFECT: obtaining quantitative characteristics of a controlled surface.

11 dwg

FIELD: physics.

SUBSTANCE: surface under test is cleared by plasma etching in an inert gas medium in the modes preventing substrate material dispersion. Right after the clearing the substrate is set horizontally, and a fluid drop of given volume is dropped onto it from the height within the 6 to 22 mm range. The time of the drop spread over the surface, between the moment the drop touches the substrate surface and till the fluid spread over the substrate surface stops, is measured. Surface finish of the substrate is defined by correlation of the obtained drop spread time and the standard dependency measured in advance.

EFFECT: increased productivity and control sensitivity.

2 dwg

Inspection device // 2322661

FIELD: inspection means for glass bottles, cans and so on inspection.

SUBSTANCE: linear or annular inspection device used for sealed vessel inspection comprises at least one chamber, at least one lightening means, at least one image processing system and case. Case encloses at least part of vessel conveyance path, at least one lightening means and at least one chamber. Inner case surfaces are clear and lusterless to provide diffused light scattering.

EFFECT: provision of more uniform light emission density due to full, scattered, non-directional and uniform light reflection or emission by inner case walls.

19 cl, 3 dwg

FIELD: finding of points of preliminary damage in structures.

SUBSTANCE: structures are loaded with growing weight and passage of optical signals in points of structures are measured by using light guides, light-emitting diode, optical radiation receiver, V-shaped fiber light guide, photoelectric signal processing unit and measuring device or computer. Structure is tightly fixed by three and more V-shaped fiber light guides in areas of possible arise of cracks. Light guides are disposed at distance of approximately 3 m one from other. Speed of crack's propagation is found from time of break of separate optical fibers and precise point of damage of light guide is found after fact of damage is testified.

EFFECT: improved precision of measurement.

2 dwg

FIELD: mechanical engineering.

SUBSTANCE: method comprises cleaning the surface, submerging the surface into the indicating composition, allowing the surface to stand in the composition for a time period, and visual or optical recording of the contrast of the indicating trace on the background of the surface to be tested in the visible radiation.

EFFECT: enhanced sensibility.

2 cl, 15 dwg, 1 tbl, 2 ex

FIELD: physics.

SUBSTANCE: device currently in use includes optical microscope, sitting vial support, vial illumination system. Besides, it accommodates digital camera, surface tension calculating unit, flotation agent activity calculating unit, video data memory, output memory, digital camera controller, bus controller, timing device, unit controlling circuit.

EFFECT: higher accuracy of surface tension calculation ensured by high-resolution digital camera, higher calculating speed with device downsizing through hardware support of computing algorithms, evaluation of parameters describing the contribution of separate groups of surface-active substances to floatation agent activity.

1 dwg

FIELD: assessment of technological processes conduction quality.

SUBSTANCE: substance of invention lies in the following: method for determination of liquid surface tension and density includes supply of gas to the inlet of gas supply tube, which is immersed at preset depth in monitored liquid, and measurement of maximum pressure in tube. Additionally quantity of gas bubbles that were supplied into liquid is measured, and by values of maximum pressure in tube and quantity of gas bubbles conclusion is made about surface tension and density of monitored liquid.

EFFECT: increase of accuracy and expansion of method functional resources.

1 dwg

FIELD: invention refers to extraction of useful components out of ores at separation of useful fossils.

SUBSTANCE: mode includes process of size reduction of ores in laboratory mill in dry, wet modes and with additives. At that in process of physical impacting they define by calculating-empirical way specific energy wasted on size reduction, measure specific surface of particles after size reduction and calculate specific surface energy of ores according to definite relation.

EFFECT: increases efficiency of process of extraction of useful components out of ores and optimizes working regimes of present apparatus used at stage of preparation of minerals.

2 dwg

FIELD: investigating or analyzing materials.

SUBSTANCE: method comprises local heating the specimen up to a given temperature by means of applying opposite temperature gradients from both sides of the site to be heated and measuring shrinking tension in the zone of creeping. The specimen is U-shaped and is heated up to a given temperature. The temperature gradient is provided by cooling. The surface tension coefficient is determined from the formula proposed.

EFFECT: enhanced precision.

2 dwg

FIELD: measuring technique.

SUBSTANCE: method comprises submerging the plate into the liquid to be measured. The vessel filled with the liquid is mounted on the balance, the balance readings is set to zero, and the plate is submerged into the liquid and then it is slowly removed from the liquid. The weight of the vessel is measured at the moment of detaching of the plate from the liquid surface and the maximum balance reading is recorded. After removing the plate, the weight of the vessel is measured again. The reading of the balance corresponding to the mass of liquid adsorbed by the plate is subtracted from the maximum balance reading, and the value obtained is used for the calculation of the interfacial tension.

EFFECT: enhanced precision.

5 dwg

FIELD: measuring technique.

SUBSTANCE: device comprises vacuum chamber that receives a vertical thread-like specimen. The horizontal transparent cylindrical sleeve is secured to the vacuum chamber. The device also has a system for generating oppositely directed temperature gradient at a given point of the thread-like specimen for forming a creeping zone, mechanical lever whose one arm is set in the vacuum chamber and connected with the thread-like specimen and other arm is arranged along the axis of the transparent sleeve and has compensating weight, and optical lever. The device is provided with means for moving the compensation weight.

EFFECT: enhanced accuracy of measurements.

1 cl, 2 dwg

FIELD: thin film physics, in particular, liquid films, surface tension of which is sensitive to their composition and to composition of surrounding environment.

SUBSTANCE: in accordance to method, for manufacturing sensitive cheap thin film evaporator-oscillators with new properties, liquid films are used made of common solutions with soap-like surfactants or chemically pure surfactants, but with special addition - noticeable proportion (1-50)% of component, that mixes well with water - dimethylsulfoxide - is additionally included in composition of soap solution for films.

EFFECT: expanded area of application of film evaporator-oscillators due to their creation on basis of new cheaper substances with high stability in broad range of temperatures.

2 dwg

FIELD: medicine, pharmacology, biology, agriculture.

SUBSTANCE: method relates to lipid structure-phase conversions in aqueous solutions, which represent important component information recording/sensing on the level of brain synaptic membranes. To perform lipid structure-phase conversions in aqueous solutions in presence of additives lipid aqueous solution and additive aqueous solution are divided by water layer being separated from said solution by membranes which are permeable only for water molecules. Lipid components of animal, plant cells and surfactants of lipid origin are used as lipids, and water-soluble substances of inorganic, organic or biological origin are used as additives.

EFFECT: method for investigation of various substance effects on lipid structure-phase conversions in aqueous solutions.

4 cl, 5 ex, 1 dwg

FIELD: measuring engineering.

SUBSTANCE: method comprises generating thermocapillary convection by laser beam in a layer of fluid on the substrate which absorb laser radiation. After the light beam is turned on, the substrate begins to liberate heat, and heat front propagates from the substrate to the free surface of fluid through the layer. Once the front attains the free surface, the heat front induces the capillary flow which results in the dynamical deformation of the free surface of the layer providing a hollow. The higher concentration of the surface-active substance, the higher temperature is required for generating thermocapillary flow and, the longer time lag required for free surface to be deformed. The deformation is indicated on the screen as the deviation of the diameter of the beam spot from its value corresponding to the reflection from the flat free surface or as change in the distribution of the spot intensity. The concentration of the surface-active substance can be judged by the time interval between the moment of the turning on of the laser beam and the moment of the onset of variations of the diameter or distribution of the spot intensity on the screen. An experimental dependence of the time interval on the individual surface-active substance concentration should be obtained. The dependence is used then as a calibration one for the measurement of concentration of this surface-active substance.

EFFECT: simplified method and reduced time consumption for measurements.

3 dwg

FIELD: chemical, paint-and-varnish and food-processing industries.

SUBSTANCE: proposed method includes pumping liquid through two similar capillaries made in form of circular passages of different length, determination of volumetric flow of this liquid and pressure differential at capillary ends and viscosity and yield point.

EFFECT: enhanced accuracy of measurements; facilitated procedure of determination of viscosity and yield point.

2 dwg

FIELD: chemical, paint-and-varnish and food-processing industries.

SUBSTANCE: proposed method includes pumping liquid through two similar capillaries made in form of circular passages of different length, determination of volumetric flow of this liquid and pressure differential at capillary ends and viscosity and yield point.

EFFECT: enhanced accuracy of measurements; facilitated procedure of determination of viscosity and yield point.

2 dwg

Up!