JPH0795623B2 - Substrate surface measurement method in direct drawing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is intended to form a thick film circuit on a substrate by ejecting a thick film circuit forming paste from the nozzle while moving the nozzle and the substrate relative to each other. The present invention relates to a substrate surface measuring method in a direct drawing device.

[Conventional technology]

A thick film circuit forming paste (hereinafter referred to as "paste") on a heat-resistant ceramic substrate such as an alumina substrate using a direct drawing device.
Is discharged to draw a predetermined circuit, and then this is baked at a high temperature to form a thick film circuit pattern.

Then, it is possible to form thick films of various shapes such as a conductor, a resistor, and an insulator depending on the type of paste discharged from the nozzle.

Such thick film circuit forming technology is used in the manufacture of hybrid ICs, and a structure in which a plurality of conductor patterns are laminated in multiple layers by sandwiching an insulator is often used according to the demand for higher density and multiple layers. 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 move in the X and Y directions, and a paste that can move vertically up and down on this substrate. This can be performed by providing a discharge nozzle and moving the XY table while numerically controlling it according to a predetermined program while discharging the paste from the nozzle.

At that time, the distance between the nozzle and the substrate is required to be maintained at about several tens of microns, and if the distance is smaller than that, the film thickness of the circuit to be formed becomes thin, and conversely, if it becomes larger, the drawing line is cut off in the middle. The drawing quality is deteriorated in both cases.

On the other hand, the ceramic plate that is the material of the substrate has a warp of about 80 μm per inch when it is extremely large, and when the pattern is already drawn or printed on the substrate, when the pattern is a conductor, it is 10 μm. .About.20 .mu.m, and in the case of an insulator such as glass, a thickness of 40 to 50 .mu.m occurs.

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

FIG. 7 shows a distance measuring principle of a height sensor of a triangulation method using laser spot light.

This height sensor 10 is a compact, high-power semiconductor laser 11
And a high-resolution, high-speed semiconductor position detector (Position Sensitive Device: hereinafter "PSD") 12
A semiconductor laser that is a light source.
The laser light from is condensed by the light projecting lens 13 and is irradiated as spot light f ₁ on the substrate 1 to be measured, and the reflected light f ₂ from the substrate 1 is emitted from the light projecting lens 13 at a predetermined interval. The light-receiving lens 14 disposed with the light-receiving surface condenses light at one point on the light-receiving surface of the PSD 12 to receive light.

Then, by the displacement of the substrate 1 in the direction of the arrow, the light receiving lens
Since the angle θ of the reflected light f ₂ collected at 14 changes, PSD1
The position of the center of gravity of the light collecting spot on 2, that is, the light receiving position X is displaced in proportion to it. The light receiving position X can be easily detected by the PSD 12.

Now, assuming that the optical axis distance between the light projecting lens 13 and the light receiving lens 14 is d and the distance between the light receiving lens 14 and the PSD 12 is F, the distance L to the substrate 1 can be obtained by the following equation.

L = d · F / X (1) [Problems to be solved by the invention] However, in the substrate surface measuring method in such a conventional direct drawing apparatus, a thick film circuit pattern is already formed on the substrate. If there is, the material of the paste forming the pattern causes an error peculiar to the material in the actual height measurement value of the substrate surface, and such measured value is used as it is as the height control data for drawing. If used, the desired drawing quality may not always be obtained.

That is, as shown in FIG. 8, a conductor pattern 101 containing a large amount of metal such as gold, silver, platinum, silver palladium, copper, etc. on the surface 1a of a substrate 1 made of a ceramic material and an insulator pattern made of insulating glass. When 102 is formed, the substrate surface 1a and the surfaces 101a and 102a of the respective patterns 101 and 102 are formed.
The height measurement values of and are different from the actual surface condition (shown by the solid line S) as shown by the phantom line S ′ in the figure.

The reason is considered as follows.

Since the surface of the conductor pattern 101 is extremely dense and flat, all the laser light from the semiconductor laser 11 of the height sensor 10 shown in FIG. 7 is reflected from the surface 101a and reaches the PSD 12, and the pattern surface 101a The actual height L is (1) above.
It can be obtained using an equation.

On the other hand, the surface 1a of the substrate 1 has fine irregularities, and a part of the projected laser light is reflected from the highest part of the surface 1a, but most of the other part is reflected from the lower part, so PS
The position of the center of gravity of the focusing spot on D12 is the position corresponding to the surface lower than the highest part of the surface 1a, and a value lower than the actual height is measured.

Further, in the case of the insulator pattern 102, the thickness of the insulating glass as a material is extremely thin as 40 to 50 μm, and even colored glass can be regarded as almost transparent, so that the incident angle of the projected laser light is glass. If it is smaller than the critical angle (about 42 degrees) of the pattern 102, the light reflected by the front surface 102a and the back surface 102b of the pattern 102 both enter the PSD 12, and the position of the center of gravity of the light collecting spot corresponds to the surface lower than the surface 102a. This is the position, 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 the substrate on which the pattern is not formed, there is no problem because the height measurement value can be uniformly corrected, but the thick film circuit pattern is already generated. However, there is a problem that the correction amount of the actually measured height data must be changed depending on the material of the pattern.

The present invention solves such a conventional problem, automatically identifies the material of the pattern formed on the substrate, and can correct the height data according to the material to measure the substrate surface in the direct drawing apparatus. The purpose is to provide a method.

[Means for Solving the Problems]

In order to achieve the above object, the present invention controls the nozzle height based on the height data of the substrate surface previously measured by a height sensor while relatively moving the nozzle and the substrate, and pastes from the nozzle. In a substrate surface measuring method in a direct drawing apparatus that discharges a thick film circuit on a substrate, the height sensor scans the entire surface of the substrate to simultaneously obtain height data and reflected light intensity data. The collected reflected light intensity data is identified to correspond to each material of the pattern formed on the substrate, to which of a plurality of areas divided by the intensity level, and to correspond to the identified area. The present invention provides a substrate surface measuring method in a direct drawing apparatus that corrects the height data according to a height data correction amount set in advance.

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 by the height sensor in advance, and the paste is discharged from the nozzle to form the thick film circuit on the substrate. In a substrate surface measuring method in a direct drawing apparatus to be formed, the height sensor scans the substrate surface over almost the entire surface to collect reflected light intensity data at a large number of points, After dividing into a plurality of areas according to the intensity level corresponding to each material of the pattern formed on the substrate and setting the height data correction amount of each area, the entire surface of the substrate is measured by the height sensor. It is also possible to rescan and collect the height data and the reflected light intensity data at the same time, and correct the height data according to the height data correction amount corresponding to the reflected light intensity data.

[Work]

By the method as described above, the height data of the entire surface of the substrate and the reflected light intensity data thereof are collected.

It has been confirmed that this reflected light intensity data converges within a specific area depending on the material of the substrate and the pattern formed on the substrate. It is possible to know the predetermined height data correction amount actually measured for each.

Therefore, if the height data measured by the height data correction amount is corrected to move the nozzle up and down,
It becomes possible to always draw a high-quality thick film circuit pattern.

In addition, if the reflected light intensity data of a plurality of points over almost the entire surface of the substrate is collected before the height measurement, it may be caused by the variation between the lots of the substrate material and the paste, the change over time, or the deterioration of the height sensor performance. Even when the reflected light intensity data or the distribution state thereof is shifted to either the high or low direction, the height data can be accurately corrected by identifying the type of each material.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6 of the accompanying drawings.

First, the outline of the direct drawing apparatus used in the present invention will be described with reference to FIGS. 2 and 3.

FIG. 2 is a perspective view showing the structure of the direct drawing apparatus. The substrate 1 is positioned and fixed by a plurality of positioning pins at a predetermined position on the XY table 2 which can move in the X and Y directions.

The nozzle 4 of the ink pen 3 is arranged perpendicularly to the XY table 2, and is held by a linear slider 6 which is driven by a motor 5 in the Z-axis direction perpendicular to the XY plane.
The paste 7 is discharged onto the substrate 1.

The above-mentioned height sensor 10 is fixed to the device fixing portion, and the height of the substrate 1 is measured to detect the unevenness of the surface, and
The intensity of reflected light on the surface of the substrate 1 can be measured, and a light amount reference piece 8 for height data calibration is provided on the XY table 2 correspondingly.

FIG. 3 is a system configuration diagram including the control system of the direct drawing apparatus. The height sensor 10 is almost the same as that shown in FIG. 7, but in this embodiment, the light projecting lens 13 and the light receiving lens 14 are used. Polarizing filters 15 and 16 are provided on the substrate 1 side with their polarization axes parallel to each other to prevent malfunction due to outside light.

Then, the laser light from the semiconductor laser 11 is projected by the projection lens 1
3, the substrate 1 is irradiated through the polarization filter 15, and the reflected light is imaged as a condensing spot on the PSD 12 through the polarization filter 16 and the light receiving lens 14.

In the PSD12, a charge corresponding to the intensity is generated at the center of gravity of the focusing spot, and the current value i ₁ , i of the photocurrent due to the charge is generated.
₂ is output in inverse proportion to the distance to the electrodes on both ends.

Therefore, when the center of gravity of the light collecting spot due to the reflected light from the substrate 1 is in the center of the PSD 12, the current values i ₁ and i ₂ are equal, and the light is reflected by the surface having a height different from the surface of the substrate 1. In that case, since the image forming point is displaced from the center, a difference occurs between the current values i ₁ and i ₂ depending on the amount of the deviation.

At this time, the distance from the substrate 1 in the height direction is (i ₁ −i ₂ ) /
Since the light amount according to the reflected light intensity received by the PSD 12 is proportional to (i ₁ + i ₂ ) and is proportional to (i ₁ + i ₂ ), the distance data and the light amount data can be obtained by the calculation units 18 and 17.

On the other hand, the XY table 2 to which the substrate 1 is fixed is driven by the motors 2a and 2b controlled by the motor controller driver 9 to move in the X and Y directions, and the motor controller driver 9 moves the nozzle 4 up and down. Motor 5 to drive
The motor controller driver 9 is also controlled by a microcomputer (hereinafter abbreviated as “microcomputer”) 20.

Further, the light amount data and the distance data obtained by the arithmetic units 17 and 18 are input to the microcomputer 20 via the I / O unit 21,
Therefore, as will be described later, the distance data (height data) is corrected by the light amount data.

Therefore, by moving the XY table 2 in the XY direction, the substrate 1
The light amount data and the distance data obtained by scanning the substrate 1 in a line shape by the height sensor 10 that moves relatively to each other are sequentially stored in the RAM in the microcomputer 20.

Memory with large capacity RAM or hard disk 30
Is used as a distance data map storage unit 31 for storing height data corrected by the microcomputer 20 and a drawing data storage unit 32 for storing drawing data input from an external controller (not shown). The drawing data is read by the microcomputer 20, the movement data of the XY table 2 and the control data of the motor 5 for moving the ink pen 3 up and down are processed by the XY table / ink pen control motor control function, and the data is sent to the motor controller driver 9. Printing is performed by moving the substrate 1 while outputting and holding the ink pen 3 at a predetermined height, and discharging the paste 7 from the nozzle 4 onto the substrate 1.

The ejection of the paste from the nozzle 4 is controlled by air pressure or the like, but since it is the same as the conventional one, its explanation is omitted here.

Next, the microcomputer 20 of this embodiment having such a configuration
The substrate surface measuring process according to FIG. 1 will be described with reference to FIGS. 4 to 6 according to the flow chart shown in FIG.

First, in step 1, the XY table 2 is driven as shown by the arrow A in FIG. 4, and the height sensor 10 scans the surface of the substrate 1 over substantially the entire surface with a predetermined pitch, and a plurality of points (for example, It collects (samples) the reflected light intensity data (light intensity data) of 2,500 points in a 50 mm square and temporarily stores it in the internal RAM. At this time, height data is not acquired.

In step 2, the maximum value and the minimum value of the collected reflected light intensity data group are obtained, and the interval is equally divided into n (for example, 30).

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

In this way, as can be seen from FIG. 5, mountain portions with a high occurrence frequency F appear at a plurality of locations (three locations in the figure), and as a result, they correspond to, for example, ceramic base, insulating glass and conductor, respectively. It is confirmed to do.

Note that these processes are performed by software using the microcomputer 20.
It is not always necessary to create such a histogram and present it to the user.

In step 4, the valleys T ₁ , T ₂ , ... Between the peaks of the histogram thus created are found and stored as material identification data.

In this process, the thick film circuit pattern that is usually formed on the substrate 1 is often a conductor pattern and insulating glass. Therefore, it suffices to be able to identify the three persons who add the ceramic substrate, which is the material of the substrate 1, to this. As shown in FIG. 5, it is sufficient if the valley can detect two points T ₁ and T ₂ .

Next, in step 5, the height sensor 10 scans the entire surface of the substrate 1 with a predetermined pitch smaller than step 1 to simultaneously measure the height data and the reflected light intensity data.

Then, in step 6, which region of the histogram in FIG. 5 the reflected light intensity T is in, that is, T <T ₁ , T ₁
Depending on whether <T <T ₂ or T ₂ <T, the height data is corrected using the correction amount corresponding to each area, that is, the material, which is stored in the ROM of the microcomputer 20 in advance. ,
The corrected height data is stored in the distance data map storage unit 31 of the memory 30.

Finally, using the corrected height data stored in the memory 30, the motor controller driver 9 moves the XY table 2 and at the same time controls the rotation of the motor 5 to move the nozzle 4 up and down to perform drawing. .

Here, the height data correction in steps 5 and 6 will be described in detail with reference to the example shown in FIG.

As shown in the upper part of the figure, the conductor pattern 101 containing a large amount of precious metal is formed on the surface 1a of the substrate 1 made of a ceramic material.
And an insulator pattern 102 made of insulating glass are formed.

In step 5, the XY table 2 is driven and the height sensor 10 scans the entire surface of the substrate 1 to measure the reflected light intensity T and the height H, and the actual measurement as shown in the middle and lower rows of the same figure. Get curves t and h.

In the diagram of the reflected light intensity T shown in the middle row, the reflected light intensity T ₁ and
When a line corresponding to T ₂ is drawn, the measured curve t has three regions where the reflected light intensity T is T <T ₁ , T ₁ <T <T ₂ , T ₂ <T. Therefore, the region of T <T ₁ is the reflection region from the ceramic substrate which is the material of the substrate 1, the region of T ₁ <T <T ₂ is the reflection region from the insulating glass which is the material of the insulator pattern 102, and T ₂ < The area T is determined to be the reflection area from the conductor pattern 101.

Then, the correction amount corresponding to the height data actually measured in each of these areas is obtained in advance by experiments and stored in the ROM of the microcomputer 20.

For example, with a conductor pattern as a reference value of 0, +50 μm for a ceramic substrate, + for an insulator pattern
If the correction value of 40 μm is stored, the measured height data can be immediately corrected in the microcomputer 20 by the correction value to obtain the correction data h ′, and the correction data can be stored in the distance data map storage unit in the memory 30. Store in 31.

As a result, in step 7, the nozzle 4 can be moved up and down to draw by using the stored height data after correction.

In the above embodiments, the most common conductor pattern and insulator pattern are described as examples of the pattern formed on the substrate of the ceramic material, but the reflected light of other formable materials is used. The intensity and its correction amount are all stored in the ROM of the microcomputer 20, and the correction amount is automatically selected by the reflected light intensity measurement by the height sensor 10,
Alternatively, in the case of a special material, the correction value input by the user through the I / O unit 21 from a keyboard (not shown),
It is also possible to correct the measured height data.

In addition, in the above-described embodiment, prior to the height measurement of the entire surface of the substrate by the height sensor, the reflected light intensities at a plurality of points on the substrate surface are measured in Steps 1 to 4 to create a histogram. Although each correction amount is identified and selected, 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 always necessary.

〔The invention's effect〕

As described above, according to the present invention, since the height sensor that measures the unevenness of the substrate collects the reflected light intensity data together with the height data, the collected reflected light intensity data forms the substrate and the surface thereof. It is possible to identify the material of the pattern and correct the height data with an appropriate height data correction value for each material, and by using the corrected height data to move the nozzle up and down, It is possible to form a high-quality drawing pattern by always maintaining an appropriate gap between the substrate and the substrate surface.

In addition, prior to detecting the height data, by collecting reflected light intensity data at a number of points on the entire surface of the substrate and setting a correction amount for the reflected light intensity data according to the distribution state,
Even if the reflected light intensity data or its distribution state shifts due to changes in the substrate material or paste between lots, changes over time, or performance deterioration of the height sensor, the height data can be accurately corrected. .

[Brief description of drawings]

FIG. 1 is a flow chart of substrate surface measurement processing according to an embodiment of the present invention, FIG. 2 is a perspective view showing the appearance of a direct drawing apparatus to which the present invention is applied, and FIG. 3 is a system configuration including a control system thereof. FIG. 4 is an enlarged perspective view showing the substrate surface measurement state similarly by the height sensor, FIG. 5 is a histogram illustrating the distribution state of the reflected light intensity on the substrate surface, and FIG. 6 is measured by the height sensor. FIG. 7 is a diagram showing the relationship between the intensity of reflected light and the correction amount of height data, FIG. 7 is an explanatory diagram showing the distance measuring principle of the height sensor, and FIG. It is a diagram showing a relationship. 1 ... Substrate, 2 ... XY table 3 ... Ink pen, 4 ... Nozzle 7 ... Paste, 10 ... Height sensor 20 ... Microcomputer 30 ... Memory, 101 ... Conductor pattern 102 ... Insulator pattern

Claims (2)

[Claims] 1. The height of a nozzle is controlled based on the height data of the substrate surface measured by a height sensor in advance while moving the nozzle and the substrate relative to each other, and the paste is ejected from the nozzle to eject the paste on the substrate. In a substrate surface measuring method in a direct drawing apparatus for forming a thick film circuit on a substrate, the height sensor scans the entire surface of the substrate to collect height data and reflected light intensity data at the same time, and collect the reflected light. The light intensity data is identified to correspond to each material of the pattern formed on the substrate, to which of a plurality of regions divided by the intensity level, and a preset high level corresponding to the identified region is identified. A method for measuring a substrate surface in a direct drawing apparatus, characterized in that the height data is corrected according to a correction amount. 2. The height of the nozzle is controlled based on height data of the surface of the substrate measured by a height sensor in advance while moving the nozzle and the substrate relative to each other, and the paste is ejected from the nozzle to eject the paste on the substrate. In a substrate surface measuring method in a direct drawing apparatus for forming a thick film circuit on a substrate, the height sensor scans the substrate surface over almost the entire surface to collect reflected light intensity data at a number of points, and collect the reflected light. The light intensity data is divided into a plurality of regions according to the intensity level corresponding to each material of the pattern formed on the substrate, and the height data correction amount of each region is set, and then the height sensor is used to The entire surface of the substrate is rescanned to collect height data and reflected light intensity data at the same time, and the height data is corrected according to the height data correction amount corresponding to the reflected light intensity data. A method for measuring the surface of a substrate in a direct drawing device.