JPH02298095A - Measuring method for substrate surface in direct drawing device - Google Patents

Abstract

PURPOSE:To enable the drawing of a thick-film circuit pattern of high quality in any time by measuring strength of reflected light as well as height of the whole surface of a substrate by scanning the whole surface of the substrate by a height sensor and by correcting the height data according to the measured intensity of the reflected light. CONSTITUTION:An X-Y table 2 is driven and a height sensor 10 scans over almost the whole surface of a substrate 1 in a predetermined pitch. The data of reflected light intensity in a plurality of points are gathered and are stored temporarily in a RAM inside. After setting a predetermined height correcting quantity according to a distribution state of the gathered data of reflected light intensity, said data are stored in a microcomputer 20 as the data for recognizing materials. Next, the height sensor 10 scans the whole surface of the substrate 1 by a predetermined pitch which is smaller than that of the last time so as to measure the height data and the reflected light intensity data at the same time. The height data are corrected by using a correcting quantity corresponding to each region stored in the microcomputer 20 previously, namely, a material. The corrected height dat are stored in a distance data map storage 31 of a memory 30. Lastly, by using the corrected height data stored in the memory 30, a drawing with a motor controller driver 9 is effected.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for forming a thick film circuit on a substrate by discharging a paste for forming a thick film circuit from a nozzle while moving the nozzle and the substrate relative to each other. The present invention relates to a method for measuring a substrate surface in a direct writing apparatus.

(Prior art) Thick film circuit forming paste (hereinafter referred to as "paste") is applied onto a heat-resistant ceramic substrate such as an alumina substrate using a direct writing device.
After drawing a predetermined circuit by discharging a thick film, a thick film circuit pattern is formed by firing it at a high temperature.

Depending on the type of paste discharged from the nozzle, thick films of various shapes such as conductors, resistors, and insulators can be formed.

This type of thick film circuit formation technology is used in the manufacture of hybrid ICs, and in response to the demands for higher density and multilayering, structures in which multiple conductor patterns are stacked in multiple layers with an insulator sandwiched in between are often used. has been done.

To form a thick film circuit using a direct drawing device, the substrate on which the circuit is to be formed is fixed on an XY table that can be moved in the X and Y directions, and a paste that can be moved up and down perpendicular to this substrate is This can be done by providing a discharge nozzle and moving the XY table under numerical control according to a predetermined program while discharging the paste from the nozzle.

At that time, it is required to maintain the distance between the nozzle and the substrate at about several tens of microns; if the distance is smaller than that, the thickness of the circuit formed will be thinner, and if it is larger, the drawn line will break midway. In either case, the drawing quality deteriorates.

On the other hand, the ceramic plate that is the material of the board has a warp of nearly 80 μm per inch in severe cases, and if the board has already been drawn or printed with a pattern,
When the pattern is a conductor, the thickness is 10 to 20 μm, and when it is an insulator such as glass, the thickness is 40 to 50 μm.

Therefore, in order to draw thick film circuits on such substrates, conventionally, an optical height sensor using laser light is provided, and the height sensor is scanned prior to the actual drawing.
The height of the substrate surface is measured at a predetermined pitch over the entire surface, the height data of each part is stored in the RAM of the microcomputer, and the nozzle is moved up and down according to the irregularity of the substrate during drawing. ing.

FIG. 7 shows the distance measurement principle of a triangulation type height sensor using a laser spot light.

This height sensor 10 uses a small, high-output semiconductor laser 1.
1 and a semiconductor device detector with high resolution and high speed response (Position 5 sensitive device detector).
e: hereinafter referred to as rPSDJ) 12, the laser beam from the semiconductor laser 11 that is the light source is focused by the projection lens 13 and irradiated onto the substrate 1 to be measured as spot light f1. , reflected light f from the substrate 1
2 is condensed and received at one point on the light receiving surface of the PSD 12 by a light receiving lens 14 disposed at a predetermined distance from the light projecting lens 13.

Then, as the substrate 1 is displaced in the direction of the arrow, the angle O of the reflected light f2 focused by the light receiving lens 14 changes.
The position of the center of gravity of the focused spot on the PSD 12, that is, the light receiving position X, is displaced in proportion to this. This light receiving position X is
It can be easily detected by PSD12.

Now, if the distance between the optical axes of the light projecting lens 13 and the light receiving lens 14 is d, and the distance between the light receiving lens 14 and the PSDI 2 is F, then the distance to the substrate 1 can be determined by the following equation.

L=d -F/X (1) [Problems to be Solved by the Invention] However, in such a conventional method for measuring the substrate surface using a direct writing device, it is difficult to measure the surface of a substrate when a thick film circuit pattern has already been formed on the substrate. If so, the material of the base I- that forms the pattern will cause an error specific to that material in the actual height measurement value of the substrate surface, and such actual measurement value may be used as height control data during drawing. When used, the desired drawing quality may not always be obtained.

That is, as shown in FIG. 8, a conductive pattern 101 containing a large amount of metal such as gold, silver, platinum, silver palladium, copper, etc. and an insulating pattern made of insulating glass are formed on the surface 1a of a substrate 1 made of a ceramic material. 102, the substrate surface 1a and the surfaces 101a of the respective patterns 101 and 102.

The height measurement value with respect to 102a is different from the actual surface condition (indicated by solid line S), as shown by virtual line S' in the figure.

The reason may be as follows.

Since the surface of the conductive pattern 101 is extremely dense and flat, the semiconductor laser 1 of the height sensor 10 shown in FIG.
The laser beam from the pattern surface 101a enters and is reflected from the surface Iota to reach the PSD 12, and the actual height L of the pattern surface 101a can be determined using the above-mentioned equation (1).

On the other hand, since the surface 1a of the substrate 1 has fine irregularities, some of the projected laser light is reflected from the highest part of the surface 1a, but most of the other light is reflected from the lower parts.
The center of gravity of the focused spot on the PSDI 2 corresponds to a surface lower than the highest part of the surface 1a, and a value lower than the actual height is measured.

In addition, in the case of the insulator pattern 102, the thickness of the insulating glass that is the material is extremely thin at 40 to 50 μI, and even colored glass can be considered almost transparent, so the incident angle of the projected laser beam is is smaller than the critical angle (approximately 42 degrees), the front surface 102a and back surface 10 of the pattern 102
Both of the reflected lights from 2b enter the PSD 12, and the center of gravity of the focused spot corresponds to a surface lower than the surface 102a, and in this case as well, a value lower than the actual height is measured.

Therefore, when drawing a new thick film circuit pattern on a substrate on which no pattern has been formed, no problem will occur because the height measurement value can be uniformly corrected, but if a thick film circuit pattern has already been formed, no problem will occur. In this case, there is a problem in that the amount of correction of the actually measured height data must be changed depending on the material of the pattern.

This invention solves these conventional problems and provides a method for measuring the surface of a substrate in a direct writing device that can automatically identify the material of the pattern formed on the substrate and correct the height data according to the material. The purpose is to provide a method.

[Means to solve the problem]

In order to achieve the above object, the method for measuring the surface of a substrate in a direct writing apparatus according to the present invention is to adjust the height of the nozzle based on the height data of the substrate surface measured in advance by a height sensor while moving the nozzle and the substrate relative to each other. In a direct writing device that controls the height and discharges paste from a nozzle to form a thick film circuit on a substrate, the height sensor scans the entire surface of the substrate and measures the height and the intensity of reflected light, The height data is corrected according to the measured reflected light intensity.

In addition, prior to height measurement, the board is scanned over almost the entire surface to measure the reflected light intensity at multiple points, and a predetermined height correction amount is set based on the distribution of the reflected light intensity. The surface is rescanned and the reflected light intensity is measured along with its height.
It is also possible to correct the measured height data using the above-mentioned height correction amount corresponding to the reflected light intensity.

[For production]

By the method described above, the height of the entire surface of the substrate and the intensity of the reflected light are measured.

It has been confirmed that the intensity of this reflected light converges within a specific area depending on the substrate and the material of the pattern formed on the substrate, so the material can be identified from the intensity of the reflected light and actual measurements for each material have been carried out in advance. The predetermined height correction amount can be known.

Therefore, by correcting the actually measured height data using the correction amount and moving the nozzle up and down, it becomes possible to always draw high-quality thick film circuit patterns.

In addition, if you measure the reflected light intensity at multiple points over almost the entire surface of the board before measuring the height, it will be possible to avoid problems such as variations between lots of the board material or paste, changes over time, or deterioration in the performance of the height sensor. Even if the reflected light intensity or its distribution state shifts in either the vertical direction, the type of each material can be identified and the height data can be accurately corrected.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 6 of the accompanying drawings.

First, the outline of the direct writing apparatus used in this invention will be explained with reference to FIGS. 2 and 3.

FIG. 2 is a perspective view showing the configuration of the direct writing apparatus, in which the substrate 1 is positioned and fixed at a predetermined position on an xy child table movable in the X and Y directions using a plurality of positioning pins.

A nozzle 4 of an ink pen 3 is arranged perpendicularly to this XY table 2, and a Z
A paste 7 is discharged onto a substrate 1 from a nozzle 4 held by a linear slider 6 that is parked in the axial direction.

The above-mentioned height sensor 10 is fixedly installed in the device fixing part, and can measure the height of the substrate 1 and detect irregularities on the surface thereof, as well as measure the intensity of reflected light on the surface of the substrate 1. X
Correspondingly, a light amount reference piece 8 for calibrating height data is provided on the Y table 2.

FIG. 3 is a system configuration diagram including the control system of the above-mentioned direct drawing apparatus, and the height sensor 10 is almost the same as that shown in FIG. Polarizing filters 15 and 16 are provided on the substrate 1 side of 14 with their respective polarization axes parallel to each other to prevent malfunction due to external light.

Then, the laser beam from the semiconductor laser 11 is transmitted to the projection lens 13. The light is irradiated onto the substrate 1 through the polarizing filter 15, and the reflected light passes through the polarizing filter 15.

The light passes through the light receiving lens 14 and is focused on the PSD 12 as a focused spot.

In the PSD 12, a charge corresponding to the intensity is generated at the center of gravity of the focused spot, and a current value tl T L2 of a photocurrent due to the charge is output in inverse proportion to the distance to the electrodes at both ends.

Therefore, when the center of gravity of the condensed spot by the reflected light from the substrate 1 is at the center of the PSD 12, the current value t1.
When i2 is equal and the light is reflected from a surface at a different height from the surface of the substrate 1, the imaging point is shifted from the center, so a difference occurs in the current value L1p4.2 according to the amount of shift.

At this time, the distance in the height direction from the substrate 1 is (il-iz)
/ (ix + iz), and the amount of light according to the intensity of reflected light received by the PSDI 2 is proportional to (tx+iz), so distance data and light amount data can be obtained by the calculation unit 18.17.

On the other hand, the XY table 2 to which the board 1 is fixed has a motor 2a controlled by a motor controller driver 9,
2b to move in the X and Y directions, and this motor controller driver 9 also controls the motor 5 that drives the nozzle 4 in the vertical direction.The motor controller driver 9 is a microcomputer (hereinafter abbreviated as "microcomputer"). 20.

Further, the light amount data and distance data obtained by the calculation units 17 and 18 are inputted to the microcomputer 20 via the 110 unit 21, where the distance data (height data) is corrected using the light amount data as described later. be exposed.

Therefore, as the XY table 2 moves in the XY directions, the height sensor 10 that moves relative to the substrate 1 scans the substrate 1 in a line, and the light amount data and distance data obtained are sequentially stored in the RAM in the microcomputer 20. be done.

A memory 30 such as a large-capacity RAM or hard disk serves as a distance data map storage section 31 that stores height data corrected by the microcomputer 20, and a drawing data storage section 32 that stores drawing data input from an external controller (not shown). The drawing data used and stored here is read into the microcomputer 20, and the XY table/ink van control motor controller f7I processes the movement data of the XY table 2 and the control data of the motor 5 that moves the ink van 3 up and down. Then, the data is output to the motor controller driver 9, the substrate 1 is moved while the ink vane 3 is held at a predetermined height, and the paste 7 is discharged onto the substrate 1 from the nozzle 4, thereby performing drawing.

Note that the discharge of the paste from the nozzle 4 is controlled by air pressure or the like, but since it is the same as the conventional method, the explanation will be omitted here.

Next, the microcomputer 2 of this embodiment having such a configuration will be explained.
The substrate surface measurement process by 0 will be explained according to the flowchart shown in FIG. 1 while also referring to FIGS. 4 to 6.

First, in step 1, the XY table 2 is driven as shown by arrow A in FIG.
For example, reflected light intensity data (light amount data) of 2,500 points at 50+l1lIl angles are collected (sampled) and temporarily stored in an internal RAM. Note that height data is not acquired at this time.

In step 2, the maximum and minimum values of the collected reflected light intensity data group are determined, and the values are equally divided into n pieces (for example, 30 pieces).

In step 3, the collected reflected light intensity data is classified into n ranks by intensity level, and the number of data for each rank, that is, the frequency of occurrence F, is arranged in order of reflected light intensity to create a histogram as shown in Figure 5. .

When this is done, as can be seen from Figure 5, peaks with a high frequency of occurrence F appear in multiple locations (three locations in the figure), and as a result of the experiment, these correspond to, for example, ceramic substrates, insulating glass, and conductors, respectively. It has been confirmed that

Note that these processes are performed by microcontroller 2 using software.
0, it is not necessarily necessary to create such a histogram and present it to the user.

In step 4, the valley between the peaks of the histogram created in this way is Tt + TZ r...
is found and stored as material identification data.

In this process, the thick film circuit pattern normally formed on the substrate 1 is often a conductor pattern and #@ edge glass, so the three types are identified by adding the ceramic base material that is the material of the substrate 1. It is sufficient if the valley can be detected at two points T 1 + T 2 as shown in FIG.

Next, in step 5, the entire surface of the substrate 1 is scanned by the height sensor 10 at a predetermined pitch smaller than that in step 1, and height data and reflected light intensity data are simultaneously measured.

Then, in step 6, it is determined in which region of the histogram in FIG. 5 the reflected light intensity T is located, that is, T<Tx
Depending on whether it corresponds to +T1<T<TZ or TZ<T, the height data is corrected using the correction amount corresponding to each area, that is, the material, which is stored in advance in the ROM of the microcomputer 20, and the correction is performed. Save the height data to memory 3
0 in the distance data map storage section 31.

Finally, using the corrected height data stored in the memory 30, the motor controller driver 9 moves the XY table 2, simultaneously controls the rotation of the motor 5, and moves the nozzle 4 up and down to draw. .

Here, the height data correction in step 5.6 will be explained in detail according to the example shown in FIG.

As shown in the upper part of the figure, a conductor pattern 1 containing a large amount of precious metal is formed on the surface 1a of a substrate 1 made of a ceramic material.
01 and an insulator pattern 102 made of insulating glass are formed.

In step 5, the XY table 2 is moved away, the height sensor 10 scans the entire surface of the substrate 1, and the reflected light intensity T and height H are measured. Obtain measured curves t and h.

When lines corresponding to the reflected light intensities TI and TZ are drawn on the diagram of the reflected light intensity T shown in the middle row, the reflected light intensities T of the measured curve t are T<Tl, Tt<T<TZ, TZ<T
There are three regions, and from the data measured in advance, T<T
The region I is the reflection region from the ceramic base material of the substrate 1, and the region Tl<T<TZ is the insulator pattern 102.
It is determined that the region where TZ<T is the region where TZ<T is the region where the reflection from the insulating glass which is the material of the conductor pattern 101 is reflected.

Then, the correction amount corresponding to the height data actually measured in each of these areas is determined in advance through experiments and is calculated by the RO of the microcomputer 20.
Store it in M.

For example, if you store correction values of +50μm for a ceramic substrate and +40μm for an in-body pattern with the reference value O for a conductor pattern, the microcomputer 20 can immediately change the actual measured height data to the correction value. Corrected data h' can be obtained by correcting the distance data h', and the corrected data is stored in the distance data map storage section 31 in the memory 30.

Thereby, in step 7, drawing can be performed by moving the nozzle 4 up and down using the stored corrected height data.

In addition, in the above embodiment, ceramic element is used.

The explanation was given using conductor patterns and insulator patterns, which are the most common patterns formed on material substrates, as examples.
All reflected light intensities and correction amounts for materials that can be formed other than this are also stored in the ROM of the microcomputer 20, and the correction amounts are automatically selected by measuring the reflected light intensity by the height sensor 10, or special If the material is made of a similar material, it is also possible to correct the actually measured height data using a correction value input by the user through the I10 unit 21 from a keyboard (not shown) or the like.

In addition, in the above embodiment, before the height sensor measures the height of the entire surface of the substrate, in steps 1 to 4, the reflected light intensity at multiple points on the substrate surface is measured to create a histogram, and the material of each part is determined based on the stiffness. Although it is possible to identify and select the respective correction amount, if the material of the pattern formed on the substrate is commonly used and the distribution range of the reflected light intensity is known in advance, , this process is not necessarily required.

〔Effect of the invention〕

As described above, according to the present invention, the height sensor that measures the unevenness of the substrate measures the height as well as the intensity of the reflected light. By identifying the material and correcting the height data with the appropriate correction value for each material, by moving the nozzle up and down using the corrected height data, the distance between the nozzle and the substrate surface can be adjusted. This makes it possible to always maintain an appropriate level and form high-quality drawing patterns.

In addition, prior to detecting height data, by measuring the reflected light intensity at multiple locations on the entire surface of the board and setting the amount of correction for the reflected light intensity depending on the distribution state, it is possible to The height data can be accurately corrected even if the reflected light intensity or its distribution state shifts due to fluctuations in the height, changes over time, or deterioration in the performance of the height sensor.

[Brief explanation of drawings]

Fig. 1 is a flowchart of substrate surface measurement processing according to an embodiment of the present invention, Fig. 2 is a perspective view showing the external appearance of a direct writing apparatus to which this invention is applied, and Fig. 3 is a system configuration including its control system. Figure, 4th
The figure is an enlarged perspective view showing the state of measurement of the substrate surface by the height sensor, Figure 5 is a histogram illustrating the distribution of the reflected light intensity on the substrate surface, and Figure 6 is the reflected light intensity measured by the height sensor. A diagram showing the relationship with the height data correction amount, and FIG. 7 is an explanatory diagram showing the distance principle of the height sensor. FIG. 8 is a diagram showing the relationship between the cross-sectional shape of the substrate surface and actually measured height data. 1... Board 2... XY table 3.
... Ink ben 4 ... Nozzle 7 ... Paste 10 ... Height sensor 20 ... Microcomputer 30 ... Memory 101 ... Conductor pattern 102 ... Insulator pattern 's4 Figure 6

Claims (1)

[Claims] 1. While moving the nozzle and the substrate relative to each other, the height of the nozzle is controlled based on the height data of the substrate surface measured in advance by a height sensor, and the paste is discharged from the nozzle. In a direct writing apparatus for forming a thick film circuit on a substrate, the height sensor scans the entire surface of the substrate to measure the height and the intensity of reflected light, and the height sensor measures the intensity of reflected light according to the measured intensity of reflected light. A substrate surface measurement method characterized by correcting the data. 2 While moving the nozzle and the substrate relative to each other, the height of the nozzle is controlled based on the height data of the substrate surface measured in advance by a height sensor, and paste is discharged from the nozzle to form a thick film circuit on the substrate. In a direct writing device for forming a substrate, the height sensor scans almost the entire surface of the substrate to measure reflected light intensity at multiple points, and a predetermined height correction amount is determined based on the distribution state of the reflected light intensity. After setting, the entire surface of the substrate is rescanned to measure the height and reflected light intensity, and the measured height data is corrected by the height correction amount corresponding to the reflected light intensity. Characteristic substrate surface measurement method.