DE102017130797A1 - Method and device for producing a desired surface profile - Google Patents

Abstract

The present invention relates to a method and apparatus (10) for producing a desired surface profile on a workpiece. The surface profiling according to the invention enables high precision with respect to the desired surface profile, for example a desired homogeneous removal. The process management is relatively simple and the structure of the device (10) is relatively simple. Turning points of a driving movement are avoided and travel movements are limited to short distances. Finally, tool surfaces are machinable that are significantly larger than the width of the tool function.

Description

The present invention relates to a method for producing a desired surface profile according to the preamble of claim 1 and to an apparatus for producing a desired surface profile according to the preamble of claim 9.

Surface profiling is a common way to impart a specific shape to a surface. This can basically be done by order or removal or combination of both.

In principle, different tools can be used for such surface profiling. Those are known which produce a direct contact with the surface, as is the case with mechanically acting tools, for example milling and the like. In such contact-forming tools, there is thus a direct contact of a mechanical part of the tool.

On the other hand, there are also tools that act contactless with respect to the surface. So these are tools where there is no direct contact of a mechanical part of the tool with the surface. Here, for example, are known Trennschweißgeräte, laser beam tools, printers, ion beam sources, plasma jet sources and the like.

The present invention is based on such contactless tools.

The problem with these contactless tools is that they always have a tool function that has a certain spatial distribution of effects that is not homogeneous. For example, a laser beam in a plane perpendicular to its propagation direction has an inhomogeneous intensity distribution. This makes it difficult to perform a desired machining of the surface.

To remedy this situation, it is already known to arrange a tool centrally over a workpiece and to rotate the workpiece relative to the tool. As a result, inhomogeneities of the tool function on the circular paths are balanced with respect to the axis of rotation, so that rotationally symmetrical surface profiles can be produced with high precision. However, the radial homogeneity of the surface profile is dependent on the width of the tool function their homogeneity across the width, which is why it is limited. More specifically, one will select a workpiece size that is substantially smaller than the tool function, so that the tool function is largely homogeneous over the workpiece.

This is for example in the US 3 456 616 A shown, in addition to a rotation of the workpiece about a workpiece axis of rotation still describes a rotation of the workpiece axis of rotation about a central axis of rotation, so a kind of planetary motion. Although this planetary motion improves the homogeneity, it does not eliminate the size limitation. In addition, the processing times are greatly extended.

Another solution is to let the workpiece stand still and to move the tool over the workpiece like a grid. Such systems use a residence time control, but in which there is an enormous machine effort and complex simulation calculations are necessary beforehand. In addition, a meander path is used for the movement of the tool over the workpiece, which significantly increases the machining time and in which deceleration and acceleration operations take place at the beginning and end of each meander line which severely stress the mechanics of the system.

It is therefore an object of the present invention to provide a surface profiling with contactless tools, which allows a high degree of precision with respect to the desired surface profile. In particular, the process management should be relatively simple and the structure of the device relatively simple. In this case, inflection points of a travel movement are preferably avoided and travel movements are limited only to short distances. Particularly preferably, tool surfaces should be machinable, which are substantially larger than the width of the tool function.

This object is achieved with the method according to the invention according to claim 1 and the device according to the invention as claimed in claim 9. Advantageous further developments are specified in the subclaims and in the following description together with the figures.

It has been recognized, on the one hand, that this task can be achieved in a surprising manner in a particularly simple manner if the tool is rotated relative to the workpiece, wherein the tool Distance of the surface normal of the workpiece and the longitudinal axis of the tool assumes at least two different values.

The method according to the invention for producing a desired surface profile by material application and / or material removal of at least one workpiece with a workpiece normal by a contactless machining tool with a tool function and a tool longitudinal axis, wherein the machining tool is rotated relative to the workpiece, is characterized by the distance between workpiece normal and tool longitudinal axis is set to at least two different values. Both values or only one value can not be equal to 0 mm.

1. i) das Werkzeug steht still und das Werkstück wird um die Werkstücknormale rotiert, wobei die Drehachse nicht identisch mit der Werkstücknormale sein muss,
2. ii) das Werkstück steht still und das Werkzeug wird auf einer Bahn gegenüber dem Werkstück rotiert und
3. iii) das Werkstück wird um die Werkstücknormale rotiert, wobei die Drehachse nicht identisch mit der Werkstücknormale sein muss, und das Werkzeug wird auf einer Bahn gegenüber dem Werkstück rotiert.

"Relative in relation to" in the context of the present invention means that the following three different cases may exist:

1. i) the tool stands still and the workpiece is rotated about the workpiece normal, the axis of rotation need not be identical to the workpiece normal,
2. ii) the workpiece stands still and the tool is rotated on a path opposite the workpiece and
3. iii) the workpiece is rotated about the workpiece normal, the axis of rotation need not be identical to the workpiece normal, and the tool is rotated on a path opposite the workpiece.

"Railway" includes not only circular paths, but also other tracks, such as elliptical tracks or other arbitrarily curved tracks.

"On a train" means that the train does not have to be completely and / or not traversed in one go, but that at least partially move on this track is sufficient. Likewise, "rotating" does not necessarily mean that there is complete rotation. For example, a workpiece could be rotated continuously around the workpiece normal and at the same time the distance between the tool longitudinal axis and tool normal can be changed.

In an advantageous development, it is provided that the tool function is rotationally symmetrical with respect to the tool longitudinal axis. Then the surface profile precision is particularly easy to produce. In addition, or if the tool function is not rotationally symmetrical, a rotation of the tool function could be additionally provided around the tool longitudinal axis.

In an advantageous development, it is provided that a rotationally symmetrical surface profile is generated. Such surface profiles can be produced particularly easily with high precision by the rotation adjustment with spacing adjustment according to the invention.

In an advantageous development, it is provided that the machining tool is selected from the group comprising ion beam sources, plasma sources, electron beam sources, sources of electromagnetic radiation or particle sources for layer deposition. This makes it possible to process surfaces very effectively.

In an advantageous development, it is provided that the workpiece normal is tilted relative to the longitudinal axis of the tool. As a result, three-dimensional surface profiles can be generated faster. In addition, it is also possible to produce undercuts in the surface profile in relation to the workpiece normal. Finally, even curved surfaces can be processed.

In an advantageous development, it is provided that the change in distance takes place with active tool function. The tool is thus switched on and the surface profiling is effective during the change in distance. This can reduce the processing time.

In an advantageous development it is provided that a processing time of the machining tool is determined for each distance.

In an advantageous development it is provided that the tool function is determined and distances and the processing times of the distances are determined by adapting the tool function to the desired surface profile. Preferably, a tilt angle of the workpiece normal relative to the tool longitudinal axis is determined. This tilt angle can be different with respect to the different distances and also change over time.

In an advantageous development, it is provided that the tool function is modeled by mathematical functions from the group of polynomial functions, the trigonometric functions and the two-dimensional Gaussian functions and the two-dimensional error functions as well as the superposition of two or more of these functions.

In an advantageous development it is provided that the workpiece is arranged on a tool holder rotatable about a rotation axis and the tool is moved on a radius with respect to the rotation axis from a first distance to the rotation axis to a second distance to the rotation axis. As a result, the method is structurally particularly easy to implement.

Independent protection is claimed for the device according to the invention for producing a desired surface profile by material application and / or material removal of at least one workpiece with a workpiece normal by a non-contact machining tool with a tool function and a tool longitudinal axis, wherein the device is set up, the machining tool relative to to rotate the workpiece, wherein the device is characterized in that the distance between workpiece normal and tool longitudinal axis is adjustable to at least two different values.

In an advantageous development, the device is set up to carry out the method according to the invention.

• 1 die erfindungsgemäße Vorrichtung in einer perspektivischen Schnittansicht,
• 2 den Werkstückhalter der erfindungsgemäßen Vorrichtung nach 1 in einer Draufsicht in einer ersten bevorzugten Ausgestaltung,
• 3 das auf dem Werkstückhalter nach 2 angeordnete Werkstück in einem Längsschnitt,
• 4 den Werkstückhalter der erfindungsgemäßen Vorrichtung nach 1 in einer Draufsicht in einer zweiten bevorzugten Ausgestaltung,
• 5 das Schema des erfindungsgemäßen Verfahrens,
• 6 den relativen Materialabtrag über der radialen Position für ein erstes Ausführungsbeispiel und
• 7 den relativen Materialabtrag über der radialen Position für ein zweites Ausführungsbeispiel.

The features and further advantages of the present invention will become apparent in the following with reference to the description of preferred embodiments in conjunction with the figures. Here are purely schematic:

• 1 the device according to the invention in a perspective sectional view,
• 2 the workpiece holder of the device according to the invention 1 in a plan view in a first preferred embodiment,
• 3 on the workpiece holder 2 arranged workpiece in a longitudinal section,
• 4 the workpiece holder of the device according to the invention 1 in a plan view in a second preferred embodiment,
• 5 the scheme of the method according to the invention,
• 6 the relative material removal over the radial position for a first embodiment and
• 7 the relative material removal over the radial position for a second embodiment.

In the 1 . 2 and 4 is the device according to the invention 10 and its workpiece holder 12 shown in various views and configurations.

It can be seen that the device 10 a vacuum chamber 13 with a housing 14 in which an ion beam source 16 as a tool with a tool longitudinal axis WL and a workpiece holder 12 are arranged. The vacuum chamber 13 has as usual means for evacuation in the form of pumps, means for gas supply and means for supplying power to the ion beam source 16 and related control technology (not shown).

The workpiece holder 12 has an axis of rotation D on to the the workpiece holder 12 can be rotated.

The ion beam source 16 can in terms of the axis of rotation D at an angle α be tilted. The distance A between workpiece holder 12 and ion beam source 16 may be, for example, a telescoping element 17 to be changed. The distance B between the parallel (ie untilted) aligned axis of rotation D and tool longitudinal axis WL For example, by means of a rail system 18 be changed, wherein in the untilted state and for a distance B = 0 mm, the axis of rotation D and the tool longitudinal axis WL lie on a line. The distance B is thus changed on an axis x, wherein the axis x on a radius with respect to the axis of rotation D lies.

The workpiece holder 12 has a diameter of 500 mm. On this workpiece holder 12 can be adjusted accordingly 2 five workpieces 19 in wafer form, for example, juxtaposing Si wafers, the workpieces 19 have a diameter of 100 mm.

embodiment

Determination of the tool function by footprint etching

Corresponding 2 became five Si wafers 19 along the x-direction on the workpiece holder 12 arranged adjacent to each other, whereby the entire width of 500 mm of the workpiece holder 12 was covered.

These wafers 19 were before with a binary photoresist mask 20 been provided as in 3 is shown schematically. This was on every wafer 19 a lateral grid 21 with a 20 μm period, ie, there were photoresist lands 22 with 10 um width and adjacent trenches 24 with 10 μm width. This allowed each ditch 24 be assigned an exact position on the x-axis.

The ion beam source 16 was arranged untilted so that their tool longitudinal axis WL on a line with the axis of rotation D of the workpiece holder 12 was.

The ion beam source 16 was the Kaufman type, which was operated with argon as a process gas and an ionic energy of 800 eV. The working distance A was 400 mm and the process pressure in the vacuum chamber was 4.0 * 10 ^-5 mbar.

The workpiece holder 12 was with the workpieces 19 at 5 revolutions per minute about the axis of rotation D rotated for a period of 30 min, with the ion source 16 stood still. Process parameters: Ion energy: 800 eV Process gas: argon Working distance: 400 mm Angle of incidence α: 0 ° Rotation speed: 5 rpm Processing time: 30 min Process pressure vacuum chamber 13: 4.0 * 10 ^-5 mbar

This made the wafers 19 in the trenches 24 etched, with the photoresist mask 20 an etching of the wafers 19 at the respective positions of the webs 22 prevented.

After completion of the etching, all wafers were 19 taken and the photoresist mask 20 removed wet-chemically. Subsequently, the depth, that is, the etching caused by the material removal, at the location of the trenches 24 measured by means of detent force microscopy 25 ,

The measured ablations were used as input data for the determination of the tool function, in this case the ablation function. In doing so, the tool function was fit by means of a nonlinear fit procedure through a superposition of 2-dimensional Gaussian and error functions to thereby determine parameters such as etch rates, standard deviations in x and y directions, plateau values and the like. The following parameters of the tool function were calculated: Maximum etching rate: 9.48 nm / min FWHM: 192.40 mm Volumenätzrate: 0.40 mm ³ / min

Homogeneous surface profile

The calculated tool function was integrated over circles with enough radii to obtain the mean and maximum deviation from the desired surface profiling. In this case, a homogeneous removal should be achieved over the entire workpiece holder surface.

In a subsequent nonlinear fit procedure, the parameters of the two distances became known with the help of the mentioned circle integrals B1 . B2 from the axis of rotation D and determines the processing times for the respective distances, so that the desired surface profiling is obtained as accurately as possible. The norms used were the L2 (least squares method) and the Min (Max (.)) Norms. The following optimal etching parameters for two distances B1, B2 were calculated: First distance B1: 107.87 mm Processing time for first distance B1: 27.15 min Second distance B2: 260.55 mm Processing time for second distance B2: 67.18 min

The inventive method was with the device 10 according to the diagram 5 carried out. More specifically, the workpiece holder 12 around the axis of rotation D continuously rotated and the ion source 16 with its tool function 26 at a first distance B1 the tool longitudinal axis WL in relation to the axis of rotation D arranged over a first specific processing time and then at a second distance B2 the tool longitudinal axis WL in relation to the axis of rotation D arranged over a second specific processing time.

In this particular case, the arrangement at the second distance could also be the first B2 and then the arrangement at the first distance B1 be made. Whether this arrangement is interchangeable ultimately depends on the desired surface profile.

To determine the precision of the generated surface profile, three wafers were used 28 corresponding 4 on the workpiece holder 12 arranged on the x-axis so that they lay directly against each other. This covered a radius range of - 50 to + 250 mm (equivalent to a diameter of 500 mm). By the rotation of the workpiece holder 12 creates a symmetrical surface profile, so that the arrangement of these three wafers 28 was sufficient.

These wafers 28 were the same as the wafers 19 with a lateral grid 21 in the form of webs 22 and ditches 24 a binary photoresist 20 been provided. During the change of the distance B from the first distance B1 to the second distance B2 was the ion beam source 16 been deactivated. The following etching parameters had been used: Ion energy: 800 eV Process gas: argon Working distance: 400 mm Angle of incidence α: 0 ° Rotation speed: 5 rpm Process pressure vacuum chamber 13: 3.8 * 10 ^-5 mbar

After the etching was completed, the photoresist mask became 20 again wet-chemically removed and measured the surface profile by atomic force microscopy, thereby etching depths at the locations of the trenches 24 to determine.

It resulted in the 6 shown relationship between the relative removal and the position on the x-axis. From this the following values could be calculated: Minimal removal based on the total workpiece holder diameter: 106.1 nm Average removal based on the total workpiece holder diameter: 107.9 nm Maximum removal based on the total workpiece holder diameter: 109.2 nm Relative deviation related to the total workpiece holder diameter: 2.8% Relative deviation based on a workpiece holder diameter of 450 mm 1.9%

It was thus possible to achieve very good precision in the generation of a homogeneous surface profile, which could be achieved by including further distances B and related processing times can be improved.

embodiment

Determination of the tool function by footprint etching

Corresponding 2 again five Si wafers 18 corresponding to a binary grid of 20 μm period 3 along the x-direction on the workpiece holder 12 arranged adjacent to each other, whereby the entire width of 500 mm of the workpiece holder 12 was covered.

The ion beam source 16 was arranged untilted so that their tool longitudinal axis WL on a line with the axis of rotation D of the workpiece holder 12 was.

The ion beam source 16 was the Kaufman type, which was operated with argon as a process gas and an ionic energy of 800 eV. The working distance A was 425 mm and the process pressure in the vacuum chamber was 4.2 * 10 ^-5 mbar. In contrast to the first embodiment, so here was the distance A has been increased to be associated with increased lattice 2 voltage and increased gas flow to the ion source 16 the half width of the tool function of the ion source 16 to enlarge.

The workpiece holder 12 was with the workpieces 18 at 5 revolutions per minute about the axis of rotation D rotated for a time of 36.2 minutes, with the ion source 16 Stood Still. Process parameters: Ion energy: 800 eV Process gas: argon Working distance: 425 mm Angle of incidence α: 0 ° Rotation speed: 5 rpm Processing time: 36.2 min Process pressure vacuum chamber 13: 4.2 * 10 ^-5 mbar

After completion of the etching, all wafers were 18 taken and the photoresist mask 20 removed wet-chemically. Subsequently, the depth was again in the place of the trenches 24 measured by means of detent force microscopy and the tool function determined as follows: Maximum etching rate: 4.98 nm / min FWHM: 280.70 mm Volumenätzrate: 0.42 mm ³ / min

Rotationally symmetric surface profile

The tool function thus calculated was in turn integrated over circles with enough radii to obtain the mean and maximum deviation from the desired surface profiling. In this case, a rotationally symmetric curve shape should over the entire workpiece holder surface which is approximately formed by means of an exponential function with polynomial second-order exponent.

In a subsequent non-linear fitting procedure, the parameters of the two distances were again determined with the help of the mentioned circle integrals B1 . B2 from the axis of rotation D and determines the processing times for the respective distances, so that the desired surface profiling is obtained as accurately as possible. The norms used were the L2 (least squares method) and the Min (Max (.)) Norms. The following optimal etching parameters for two distances B1, B2 were calculated: First distance B1: 200.00 mm Processing time for first distance B1: 4.07 min Second distance B2: 400.00 mm Processing time for second distance B2: 158.75 min

To determine the precision of the generated surface profile, three wafers were used 28 analogous to 4 on the workpiece holder 12 arranged on the x-axis so that they lay directly against each other. This covered a range of -50 mm to + 250 mm on the x-axis. Again, there were three wafers because of rotational symmetry 28 sufficient.

These wafers 18 were identical to the first embodiment with a binary grid in the form of webs 22 and ditches 24 a photoresist 20 been provided. During the change of the distance B from the first distance B1 to the second distance B2 was the ion beam source 16 been deactivated. The following etching parameters had been used: Ion energy: 800 eV Process gas: argon Working distance: 425 mm Angle of incidence α: 0 ° Rotation speed: 5 rpm Process pressure vacuum chamber 13: 4.4 * 10 ^-5 mbar

After the etching was completed, the photoresist mask became 20 again wet-chemically removed and measured the surface profile by atomic force microscopy, thereby etching depths at the locations of the trenches 24 to determine.

It resulted in the 7 shown relationship between the relative removal and the position on the x-axis. For better clarity, the surface profile is about the axis of rotation D shown mirrored. This obtained surface profile (dots) corresponded very well to the desired surface profile (solid line). Only in the area of the rotary axis D There are slight deviations of 2.5 nm between generated and desired surface profiling.

It was thus possible to achieve a very good precision in the production of the desired surface profile, by including further distances B and related processing times can be improved.

Although the invention has been explained with reference to embodiments in which a surface profiling was carried out by ablation, it is clear that the invention is also effective in a material application. In addition, a combination of erosion and order could take place. For this purpose, two different tools could be used.

From the foregoing, it has become clear that the present invention provides surface profiling with non-contact tools that enables high precision with respect to the desired surface profile. The process management is relatively simple and the structure of the device is relatively simple. Turning points of a driving movement are avoided and Travel movements are limited to short distances. Finally, tool surfaces are machinable that are significantly larger than the width of the tool function.

Unless otherwise indicated, all features of the present invention may be freely combined. The features described in the description of the figures can, unless stated otherwise, be freely combined with the other features as features of the invention. In this case, representational features of the device can also be reworded as part of a method to process features use and reformulated process characteristics in the context of a device features of the device.

LIST OF REFERENCE NUMBERS

10

inventive device

12

Workpiece holder

13

vacuum chamber

14

Housing of the vacuum chamber 13

16

Ion beam source, tool

17

telescopic element

18

rail system

19

Workpieces, Si wafers

20

binary photoresist mask

21

lateral grid

22

Photoresist webs

24

trenches

25

Measuring points of the atomic force measurement

26

tool function

28

wafer

α

tilt

A

Distance between workpiece holder 12 and ion beam source 16

B

Distance between rotation axis D and tool longitudinal axis WL

B1

first distance

B2

second distance

D

axis of rotation

WL

tool longitudinal axis

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 3,456,616 A [0008]

Claims (10)

A method for producing a desired surface profile by material application and / or material removal of at least one workpiece with a workpiece normal by a contactless machining tool with a tool function and a tool longitudinal axis, wherein the machining tool is rotated relative to the workpiece, characterized in that the distance between Workpiece standards and tool longitudinal axis is set to at least two different values. Method according to Claim 1 , characterized in that a rotationally symmetrical surface profile, preferably a homogeneous removal is generated. Method according to Claim 1 or 2 , characterized in that the machining tool is selected from the group consisting of ion beam sources, plasma sources, electron beam sources, sources of electromagnetic radiation and particle sources for the film deposition. Method according to one of the preceding claims, characterized in that the workpiece normal is tilted relative to the longitudinal axis of the tool tilted. Method according to one of the preceding claims, characterized in that the change in distance takes place with active tool function and / or that a processing time of the machining tool is set for each distance. Method according to one of the preceding claims, characterized in that the tool function is determined and distances and the processing times of the distances are determined by adjusting the tool function to the desired surface profile, wherein preferably also a tilt angle of the surface normal of the workpiece relative to the tool longitudinal axis is determined. Method according to Claim 6 , characterized in that the tool function is modeled by mathematical functions from the group of polynomial functions, the trigonometric functions, the two-dimensional Gaussian functions and the two-dimensional error functions as well as the superposition of two or more of these functions. Method according to one of the preceding claims, characterized in that the workpiece is arranged on a rotatable about an axis tool holder and the tool is moved on a radius with respect to the axis of rotation from a first distance to the axis of rotation to a second distance from the axis of rotation. Device (10) for producing a desired surface profile by material application and / or material removal of at least one workpiece with a workpiece normal by a contactless machining tool (16) with a tool function (26) and a tool longitudinal axis (WL), wherein the device (10) set is to rotate the machining tool (16) relative to the workpiece, characterized in that the distance (B) between workpiece normal and tool longitudinal axis (WL) is adjustable to at least two different values. Device after Claim 9 , characterized in that the device is adapted to the method according to one of Claims 2 to 8th perform.

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