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EP-4737056-A2 - METHODS AND SYSTEMS FOR MACHINING PRECISION MICRO HOLES INTO THICK CERAMIC SUBSTRATES

EP4737056A2EP 4737056 A2EP4737056 A2EP 4737056A2EP-4737056-A2

Abstract

A combination of a liquid jet and a mechanical rotary tool can be used to machine precision micro holes in thick substrates. A liquid-jet guided laser can be used to rapidly drill core holes into the ceramic substrate. A sensor can be applied to detect the cut through point of the liquid-jet guided laser drilling step to allow a rapid and closed-loop controlled machining process. The substrate can be heated up for speeding up a liquid-jet guided laser drilling process. A mechanical tool such as a drill, a reamer or a mill can be applied to finish the core holes to a desired bore diameter. The mechanical tool cutting main surface can preferably consist of a diamond material. An inspection camera and illumination system can be applied to inspect each mechanically finished bore as part of the drilling process.

Inventors

  • GAEBELEIN, JENS GUENTER
  • GIEBMANNS, Ralf
  • HRIBAR, JEROEN

Assignees

  • Avonisys AG

Dates

Publication Date
20260506
Application Date
20210731

Claims (15)

  1. A method of forming a hole through a substrate using a liquid-jet guided laser beam, the method comprising: directing a column of liquid at the substrate; directing a laser beam into the column of liquid and at the substrate; and moving the column of liquid and the laser beam on the substrate along a closed shape of the hole.
  2. The method of claim 1, further comprising at least one of: moving the column of liquid and the laser beam on the substrate along the closed shape multiple times; and smoothing the hole after forming the hole using the column of liquid and the laser beam.
  3. The method of claim 1, wherein at least one of: the hole extends entirely through the substrate; and the hole is an elongated slot.
  4. The method of claim 1, further comprising flowing a gas around and coaxially with the column of liquid and the laser beam.
  5. The method of claim 1, wherein: the directing the column of liquid includes directing the column of liquid at a first side of the substrate; the directing the laser beam includes directing the laser beam into the column of liquid and at the first side of the substrate; and the moving includes moving the column of liquid and the laser beam on the first side of the substrate along the closed shape of the hole; and the method further includes: directing a second column of liquid at a second side of the substrate, the second side opposite the first side; directing a second laser beam into the second column of liquid and at the second side of the substrate; and moving the second column of liquid and the second laser beam on the second side of the substrate along the closed shape of the hole.
  6. The method of claim 1, wherein the hole is between 75 and 99% of a final dimension of the hole.
  7. The method of claim 1, wherein the substrate comprises at least one of silicon, silicon carbide, aluminum nitride, silicon nitride, titanium nitride, boron carbide, ceramic matrix composite (CMC), or metal matrix composite (MMC).
  8. The method of claim 1, further comprising heating the substrate during the moving of the column of liquid and the laser beam on the substrate.
  9. The method of claim 8, wherein the heating the substrate includes at least one of: heating the substrate by flowing a liquid over the substrate using a nozzle; heating the substrate using an infrared light source; heating the substrate using an inductive heat source; and heating the substrate by submerging the substrate in a fluid.
  10. The method of claim 8, wherein the heating includes heating the substrate by completely submerging the substrate in the fluid.
  11. The method of claim 8, wherein the heating the substrate includes heating the substrate using a heated gas.
  12. The method of claim 1, further comprising heating the substrate before the moving of the column of liquid and the laser beam on the substrate.
  13. The method of claim 1 further comprising: detecting a cut through of the hole through the substrate; and based on the detection of the cut through of the hole, selectively stopping: the directing of the column of liquid at the substrate; and the directing of the laser beam into the column of liquid.
  14. The method of claim 13 wherein the detecting the cut through includes at least one of: detecting the cut through using at least one of an optical sensor and an acoustic sensor; and detecting the cut through when an increase in at least one of light and sound is measured by the at least one of the optical sensor and the acoustic sensor.
  15. The method of claim 13 further comprising: outputting light onto the substrate using a light source with a first wavelength that is different than a second wavelength of the laser beam, wherein the detecting the cut through includes detecting the cut through based on detection of light of the first wavelength by an optical sensor.

Description

Background Precision components, such as gas distribution and uniformity plates for semiconductor processing equipment, typically require hundreds or even thousands of small precision holes machined into thick ceramic substrates. For considerations of contamination avoidance to a Silicon or Silicon Carbide product wafer, these gas distribution and uniformity plates are typically made out of equally pure or purer materials such as Silicon or Silicon Carbide. In addition to the large number of holes, these holes require a high level of surface finish. The inner wall of each hole must be smooth, mirror-alike, to avoid adherence of unwanted particles that can potentially contaminate the actual product wafer. To ensure stable and repeatable gas distribution, the entrance as well as the exit of each hole must have a sharp edge without any circumferential damage. Today, holes in gas distribution and uniformity plates are made in different ways. Holes can either be drilled sequentially using a drill bit. Holes can also be made sequentially using an electric discharge machining process in which the material inside the hole is eroded by a wire. In another way all holes, or groups of holes, can be machined simultaneously using an ultrasonic plate that removes the material inside the holes by means of ultrasonic vibration applied to a pin pattern that is inverse to that of the holes to be machined. Alternatively, all holes, or groups of holes can be machined simultaneously using an electric discharge machining process by means of an electrode plate with a pin pattern that is inverse to that of the holes to be eroded. Whereas the methods of producing the holes simultaneously via ultrasonic processing or electric discharge machining can be relatively quick, typically each hole requires a post-processing step, such as reaming, to achieve the desired mirror-alike surface finish of each hole. Drilling the holes sequentially with a milling tool can typically achieve the desired mirror-alike surface finish without any post-processing. However, drilling with a mechanical drilling tool can introduce an increased risk of material chipping on the entrance and in particular on the exit side of the hole. In addition, there is substantial wear to the drilling tool and limited tool lifetime when processing ceramic materials such as, but not limited to Silicon and Silicon Carbide. A typical gas distribution and/or uniformity plate can be 10-15mm thick and have 1000-2000 holes with a diameter of 0.2 - 0.8mm. Each hole can take 3-4 minutes to drill. If the drill bit breaks at for example hole 1480 of 1500, the entire substrate plate can potentially be scrapped, and many hours of machining work are lost. Thus, there is a substantial need for an improved and more efficient method for machining many small holes into thick ceramic substrates. A person skilled in the art will appreciate and understand that the present invention is not limited to holes in gas distribution and uniformity plates only but finds applicability to a wider range of technical ceramic materials and applications that require precision holes. Summary of the embodiments In some embodiments, the present invention discloses methods and systems to machine precision micro holes in thick substrates. The substrate can be a ceramic material into which hundreds, or even thousands of holes are machined. The holes can be created by applying a hybrid process in which a core hole drilling process and a hole finishing process are applied. A liquid-jet guided laser can be used to rapidly drill core holes into the ceramic substrate. A sensor can be applied to detect the cut through point of the liquid-jet guided laser drilling step to allow a rapid and closed-loop controlled machining process. The substrate can be heated up for speeding up a liquid-jet guided laser drilling process. A mechanical tool such as a drill, a reamer or a mill can be applied to finish the core holes to a desired hole diameter. The mechanical tool cutting main surface can preferably consist of a diamond material. An inspection camera and illumination system can be applied to inspect each mechanically finished hole as part of the drilling process. Brief description of the drawings Fig. 1A - 1B illustrate a substrate with a series of holes or bores according to some embodiments.Figs. 2A - 2B illustrate configurations for hybrid processing of holes in a substrate according to some embodiments.Figs. 3A - 3C illustrate flow charts for forming a hole in a substrate according to some embodiments.Fig. 4 illustrates a configuration of a liquid-jet guided laser head according to some embodiments.Fig. 5A - 5B illustrate a method for making holes in a substrate with a liquid-jet guided laser beam according to some embodiments.Figs. 6A - 6B illustrate a sidewall roughness of the holes according to some embodiments.Fig. 7 illustrates a flow chart for forming an initial hole in a substrate according to some embodiments.Figs.