Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B13/00—Measuring arrangements characterised by the use of fluids
  • G01B13/02—Measuring arrangements characterised by the use of fluids for measuring length, width or thickness
  • G01B13/06—Measuring arrangements characterised by the use of fluids for measuring length, width or thickness for measuring thickness
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B13/00—Measuring arrangements characterised by the use of fluids

Definitions

• the present invention relates to a device for automatic and contactless measurement of the volume of a layer deposited on a substrate. It applies to deposits made for electronic circuits by hybrid microelectronics technologies.
• the device according to the invention makes it possible to measure the equivalent of a volume; we could just as easily measure a thickness, we would therefore have much richer information than just measuring the thickness.
• the "thickness” measured could in this case be called “topological thickness”.
• a hybrid circuit for example consists of an electrically insulated substrate on which are deposited different layers of electrically conductive materials, resistive linearly or not, dielectric or insulating.
• the measurement by backscattering of beta rays faces the same difficulty as previously since it depends directly on the composition of the material deposited. Generally, a difference of 20% in the atomic numbers of the atoms constituting the substrate and the deposit is also necessary; this prohibits measurements on dielectric and insulator. Measurement by eddy current requires either non-conductive deposits on non-magnetic metals or conductive deposits on less conductive substrates. These limits generally prohibit it in hybrid microelectrics, mainly when one wants to carry out a measurement in wet which is the purpose of the control of screen printing machines.
• Elipsometry and spectrophotometry generally used for the thickness measurement of oxides and nitrides, are not at all adapted to the types of deposits used in hybrid microelectronics.
• the methods based on the Hall effect, the microresistance measurement or the coulometric measurement are suitable for metals but not for ceramic materials, moreover they are not compatible with a "wet" measurement.
• Profilometers are widely used in hybrid microelectronics, but on the one hand they do not allow the measurement in wet and on the other hand the measurement is very localized, since there is only one section in a given plane and not the whole volume. Finally, they are slow and difficult to integrate into a chain of automatic measurements.
• Optical cutting microcospes are also widely used in hybrid microelectronics, they allow contactless measurement but they have many drawbacks. They require an optical focus which complicates automation and on the other hand, their field is very limited and it is impossible by construction to visualize the whole of a section even for a width as small as 1mm.
• the aim of the present invention is to remedy all of these drawbacks by presenting a principle of contactless, automatic measurement, making it possible to measure not just a simple thickness, but an equivalent topological thickness of a volume.
• This non-contact measurement method however has many disadvantages: 1 - It is not suitable for wet measurement due to deformations of the liquid layer by the force of the gas jet.
• the aim of the present invention is to remedy these drawbacks by proposing a method and a device for contactless measurement of an equivalent topological thickness of a volume which we will call (e v ).
• the invention relates to a method of measuring e v on a deposit made on a substrate characterized in that it comprises the following phases:
• a gas injection at constant pressure is carried out above the bare substrate near the resistance, this makes it possible to zero the level of the liquid in the measurement column.
• a second injection of gas above the surface of the deposit makes it possible to measure the increased seed pressure due to this excess thickness and therefore to determine the thickness of the deposit by reading on the column of liquid.
• a characteristic of the invention consists in using a nozzle whose shape is homotetic to that of the deposit to be measured. This essential characteristic allows us to measure the equivalent of a volume.
• the flow of gas on the deposition surface depends directly on its shape, which makes it possible to integrate all of the irregularities in the section by a simple pressure measurement.
• the shape nozzles can be produced by electro-erosion or any other method.
• the invention also aims to ent a device for implementing the method and making it possible to automate the measurement on the maximum sensitivity of the measurement and for pressures of compatible ejection of the wet measurement.
• FIG. 1 shows a perspective view of a substrate with deposits of different shapes
• FIG. 2 shows a general diagram of the topological thickness measurement device according to the invention
• FIG. 5 shows the shape of the topological thickness measurement curves as a function of the height of the liquid column.
• FIG. 1 there is shown in (l) a substrate on which are deposited several layers, for example three in number, identified in (2) (3) and (4) and made of a resistive material for example.
• the measurement of the thickness e v is carried out in wet conditions, therefore before drying and before cooking.
• the nozzles identified in (5) (6) and (7) according to their shapes allow, by being homotetic of the shapes of the resistors but remaining inscribed therein, to integrate all the variations in thickness of the deposit because the flow air streams is directly related to the linear flow resistance.
• the nozzle (5) will have a square section if the deposit (2) has a square shape, but a circular section in this case there also gives good results if the circle is inscribed in the square formed by the resistance.
• the nozzles (6) and (7) are of rectangular sections, because the shape of the resistors (3) and (4) is rectangular as can be seen in the figure (2), the substrate (1) is placed on a support (8) which maintains the substrate by suction or by any other method of holding.
• a displacement table (9) integral with (8) can move laterally in x and vertically in z by means of an electric motor (10) for example.
• the control of displacements x or z is given by a computer (11) which will manage the different phases of the topographic logic thickness measurement using a step or increment counter (12) and various usable peripherals (13) to record the measurements, print them and directly order the screen printing machine or the machine that made the deposit.
• Figure 3 shows an example of the use of the device applied to screen printing inks to make hybrid modules - we observe that it is possible, by plotting the trend curve which is freed from momentary variations, to anticipate corrections on the machine or even stop. He is in possible effect of knowing according to the frequency of the measurements retained, in how many minutes for example, the parts will come out of the tolerances; we immediately see the immediate benefits that can be derived from such a measure to improve manufacturing yields.
• the computer (11) is connected to the topological thickness sensor by means of a level measurement of the liquid column (14) carried out at (15). This leveling can be done using different sensors:
• the level of the fixed liquid column will be maintained and the position of the substrate (1) will be varied by means of the table (9).
• FIG. 5 shows the appearance of the curves observed experimentally by different forms of nozzle, the linearity zones have been represented at 1% for example, it can be observed that the linear zones move away very quickly depending on the diameter of the reference inlet nozzle (16) in FIG. 2 which determines the pressure P and according to the section of the outlet nozzle marked (20) in FIG. 2. This explains the difficulties of using a thickness measurement system at air pressure if it is not automatically brought back into its maximum linearity zone. Since the liquid column is used as a reference, the measurement of e v will be deduced from the number of increments in the z axis made by the table (9)
• the device will therefore carry out the following operations:
• the computer (11) generates the information necessary for the X or XY movement of the table (9) so that the deposit (2) faces the appropriately shaped nozzle (20) .
• the air injected under low pressure P 2 will leave the form nozzle (20), the computer (11) will then generate rise information along the z axis at the table (9).
• the table (9) will approach the substrate (1) up to a distance called reference z ref which will be determined as we have explained, by means of the level sensors on the liquid column (14).
• This height z ref corresponds to the maximum sensitivity of the measurement of e v .
• the reference voltage V ref generated by the photodetector diodes (23) or (24) will be equal to Vs.
• This signal Vs received by the computer (11) will command a lateral movement X of the table (9) so that that the deposit
• the table will therefore raise the substrate (1) towards the nozzle (20) until the liquid (14) again closes the diode (21), that is to say until the reference pressure P ref is again obtained.
• the distance between the substrate and the nozzle will again be equal to z ref.
• the substrate (1) has therefore moved in height by a distance equal to e, that is to say at the integration of the volume of the deposit (2) thanks to the shaped nozzle (20).
• the computer (11) will therefore only have to count the number of increments traversed by the table (9) at each of the 2 measurement operations, by means of the counter (12) and by difference we obtain the number of increments corresponding to e v .
• the calculator will multiply the number of increments by 0.1 to determine e v .
• the method according to the invention also applies by keeping the substrate (1) fixed and by moving the nozzle (20) and its support (19) without departing from the scope of the invention.
• topological thickness measurement device was made on a screen printing chain during conductor and resistance deposits; linear regression connecting the inverse of the resistance

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Measuring Arrangements Characterized By The Use Of Fluids (AREA)
• Length Measuring Devices With Unspecified Measuring Means (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=9279961

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (5)

Family Cites Families (8)

• 1982
  • 1982-12-10 FR FR8220723A patent/FR2537716B1/fr not_active Expired
• 1983
  • 1983-12-08 JP JP59500041A patent/JPS60500184A/ja active Pending
  • 1983-12-08 US US06/641,965 patent/US4604892A/en not_active Expired - Fee Related
  • 1983-12-08 WO PCT/FR1983/000246 patent/WO1984002394A1/fr not_active Application Discontinuation
  • 1983-12-08 EP EP83903803A patent/EP0128167A1/de not_active Withdrawn
• 1984
  • 1984-08-10 FI FI843173A patent/FI843173A/fi not_active Application Discontinuation

Non-Patent Citations (1)

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