Search

DE-102019009420-B4 - Substrate processing methods

DE102019009420B4DE 102019009420 B4DE102019009420 B4DE 102019009420B4DE-102019009420-B4

Abstract

Method for processing a substrate (2) having a first surface (4) with at least one parting line (12) formed thereon and a second surface (6) opposite the first surface (4), wherein a back side layer (14) is formed on the second surface (6) and the method comprises: Applying a laser beam (LB) to the substrate (2) from the side of the first surface (4), wherein the substrate (2) is made of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) in a state in which a focal point of the laser beam (LB) is located at a position within the substrate (2) that is closer to the second surface (6) than to the first surface (4), such that several alignment marks (16) are formed in the backside layer (14) and/or in a region of the second surface (6) where the backside layer (14) is not present, and Removal of substrate material along the at least one separation line (12) from the side of the second surface (6) by using a substrate material removal agent (26), wherein the alignment marks (16) are used to align the substrate material removal agent (26) relative to the at least one dividing line (12).

Inventors

  • Karl Heinz Priewasser
  • Tzanimir Arguirov
  • Yasuyoshi Yubira

Assignees

  • DISCO CORPORATION

Dates

Publication Date
20260513
Application Date
20190329

Claims (8)

  1. Method for processing a substrate (2) having a first surface (4) with at least one parting line (12) formed thereon and a second surface (6) opposite the first surface (4), wherein a back side layer (14) is formed on the second surface (6) and the method comprises: Applying a laser beam (LB) to the substrate (2) from the side of the first surface (4), wherein the substrate (2) is made of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) in a state in which a focal point of the laser beam (LB) is located at a position within the substrate (2) that is closer to the second surface (6) than to the first surface (4), such that several alignment marks (16) are formed in the back side layer (14) and/or in a region of the second surface (6) where the back side layer (14) is not present, and removing substrate material along the at least one parting line (12) from the side of the second surface (6) by using a substrate material removal means (26), wherein the alignment marks (16) are used to align the substrate material removal means (26) relative to the at least one parting line (12).
  2. Procedure according to Claim 1 , in which the back side layer (14) is a metal layer.
  3. Procedure according to Claim 1 or 2 , further comprising attaching a protective cover (30) to the first surface (4), wherein the protective cover (30) is made of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) through the protective cover (30).
  4. A method according to one of the preceding claims, further comprising applying a laser beam (LB) to the substrate (2) from the side of the first surface (4), wherein the substrate (2) consists of a material that is transparent to the laser beam (LB), and the laser beam (LB) is applied to the substrate (2) at least at several positions along the at least one dividing line (12) such that several modified areas (18) are formed in the substrate (2).
  5. Method according to one of the preceding claims, wherein the substrate material is mechanically removed along the at least one separation line (12), in particular by mechanically cutting the substrate (2) along the at least one separation line (12).
  6. Procedure according to one of the Claims 1 until 4 , wherein the substrate material is removed along the at least one separation line (12) by laser cutting, in particular by laser ablation.
  7. Method according to one of the preceding claims, wherein the substrate material is removed only along a part of the thickness of the substrate (2) in the direction from the second surface (6) to the first surface (4).
  8. A method according to any of the preceding claims, further comprising applying an external force to the substrate (2) after substrate material has been removed along the at least one dividing line (12), so that the substrate (2) is divided along the at least one dividing line (12).

Description

Technical field The present invention relates to a method for processing a substrate which has a first surface with at least one separating line formed thereon and a second surface which is opposite the first surface. Technical background On substrates such as wafers, for example semiconductor wafers, electronic components such as integrated circuits (ICs), low-integration devices (LSIs), and light-emitting diodes (LEDs) are formed by providing a component area on a front surface of the substrate. The substrate can be a wafer made of, for example, silicon carbide (SiC), gallium nitride (GaN), gallium arsenide (GaAs), silicon (Si), or similar materials. The electronic components can be, for example, power semiconductor devices designed for energy-efficient products. In a semiconductor device manufacturing process, a wafer containing a component area with multiple components separated by several parting lines (also called "roads") is divided into individual dies. This manufacturing process typically includes a cutting step to slice the wafer along the parting lines to obtain the individual dies. The wafer can be sliced along the parting lines from either its front or back side. In an optical device fabrication process, an optical device layer, consisting, for example, of an n-type nitride semiconductor layer and a p-type nitride semiconductor layer, is formed on the front face of a single-crystal substrate, such as a sapphire, silicon carbide, or gallium nitride substrate. The optical device layer is partitioned by dividing lines to define separate regions in which optical devices, such as light-emitting diodes (LEDs) and laser diodes, are formed. By depositing the optical device layer on the front face of the single-crystal substrate, an optical device wafer is formed. The optical device wafer is then partitioned, for example, by cutting, along the dividing lines to separate the regions containing the optical devices, thus obtaining the individual optical devices as chips or dies. In engineering, a common method for dividing such substrates is to cut the substrate from its front side, where the parting lines are formed, for example, by blade cutting or laser cutting along the parting lines. This significantly simplifies the alignment of a cutting tool relative to the parting lines. However, since the component area is also located on the front side of the substrate, the quality of the components can be compromised by the cutting process. In particular, problems such as chipping on the front and/or back side and a reduction in the die strength of the resulting chips or dies frequently occur. To avoid these problems, it was suggested that the substrate be cut from the back side along the parting lines. However, this approach significantly complicates the alignment of the cutting tool relative to the parting lines and substantially reduces its alignment accuracy. The reduction in alignment accuracy typically has to be compensated for by widening the parting lines to increase the positioning tolerances of the cutting tool. However, such widening of the parting lines reduces the number of components that can be placed on the substrate, which impairs manufacturing efficiency and leads to a waste of substrate material. This problem is particularly pronounced in the case of expensive substrate materials such as SiC and GaAs. The problems described above are further exacerbated if a backing layer, such as a metal layer, is present on the back of the substrate. The presence of such a backing layer typically makes it more difficult to detect the parting lines from the back of the substrate, thus further complicating the alignment of the cutting tool. In particular, the backing layer can block the transmission of light in the visible and/or infrared (IR) range. For example, if two separate cameras are used to image the substrate simultaneously from its front and back sides in order to align the cutting tool relative to the parting lines, it is very difficult to precisely align the cameras, which usually results in poor alignment accuracy. Therefore, there remains a need for a method for processing a substrate that makes it possible to process the substrate in an accurate and efficient manner. US 2015 / 0 079 761 A1 discloses a method for cutting a wafer having a back side with a metal coating. In this In this process, a pattern is formed in the metal coating by applying a laser beam. Summary of the invention Accordingly, an objective of the present invention is to provide a method for processing a substrate that enables the substrate to be processed accurately and efficiently. This objective is achieved by a substrate manufacturing method with the technical features of claim 1. Preferred embodiments of the invention are set forth in the dependent claims. The disclosure provides a method for processing a substrate comprising a first surface with at least one parting line formed thereon and a second surface opposite the f