Purging gas laminar flow design and specific patterns for laser processing

Abstract

The present disclosure describes systems and methods for designing a wafer anneal chamber that combines laminar or near-laminar flow of a purge gas over the wafer, higher flow rates and pressures in the upper portion of the chamber, and specific travel of the laser pattern relative to the direction of the laminar flow of the purge gas.

Description

[0001] Citations of relevant applications

[0002] This application claims priority and benefit to U.S. Provisional Patent Application No. 63 / 728,957, filed December 6, 2024, entitled “Design and Specific Patterning of Purge Gas for Laser Processing,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to a design and specific pattern for a purge gas laminar flow for laser processing. Background Technology

[0004] By comparing the present method and system with conventional laser annealing methods and systems by referring to the accompanying drawings and certain aspects set forth in the remainder of this specification, the limitations and disadvantages of conventional methods and systems will become apparent to those skilled in the art. Summary of the Invention

[0005] Systems and methods for designing controlled atmosphere chambers, as shown in at least one figure and / or described in conjunction with at least one figure, are more fully described in the claims. Attached Figure Description

[0006] Figure 1 A side view of an exemplary wafer annealing chamber according to various example implementations of this disclosure is shown. Detailed Implementation

[0007] The following discussion provides various examples of annealing chambers. Such examples are non-limiting, and the scope of the appended claims should not be limited to the specific examples disclosed. In the following discussion, the terms "example" and "for example" are non-limiting.

[0008] The accompanying drawings illustrate a general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring this disclosure. Furthermore, elements in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements in the drawings may be exaggerated relative to others to aid in understanding the examples discussed in this disclosure. The same reference numerals in different drawings denote the same elements.

[0009] The term "or" refers to any one or more items in a list that are linked by "or". For example, "x or y" means any element in the three-element set {(x), (y), (x, y)}. As another example, "x, y or z" means any element in the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}.

[0010] The terms “comprises”, “comprising”, “includes”, and / or “including” are “open-ended” terms and specify the presence of the stated feature but do not exclude the presence or addition of one or more other features.

[0011] The terms “first,” “second,” etc., may be used herein to describe various elements, and these elements should not be limited by these terms. These terms are used only to distinguish one element from another. Thus, for example, a first element discussed in this disclosure may be referred to as a second element without departing from the teachings of this disclosure.

[0012] Unless otherwise specified, the term "connected" can be used to describe two elements that are in direct contact with each other or to describe two elements that are indirectly connected through one or more other elements. For example, if element A is connected to element B, then element A can be in direct contact with element B or indirectly connected to element B through an intermediate element C. Similarly, the terms "on top of" or "on" can be used to describe two elements that are in direct contact with each other or to describe two elements that are indirectly connected through one or more other elements.

[0013] This disclosure relates to laser annealing to produce improved electrical contacts for semiconductor devices.

[0014] Laser energy is required to convert the deposited metal film and the surface layer of the underlying silicon carbide (SiC) substrate into a silicide ohmic contact. However, this laser energy causes partial vaporization of the target metal and the substrate. Vaporization can generate debris clouds that partially absorb the incident laser energy. Vaporization can also contaminate nearby unannealed surfaces. The resulting partial absorption or scattering causes changes in the laser energy delivered to the target region, thereby reducing process efficiency.

[0015] This disclosure relates to laser annealing to produce improved electrical contacts for semiconductor devices.

[0016] Figure 1 A side view of an example wafer annealing chamber 100 according to various example implementations of this disclosure is shown.

[0017] The laser annealing chamber 100 is designed to optimize debris management and ensure uniform annealing of SiC wafers. At the heart of the design is a wafer support platform 101, characterized by a rectangular or cylindrical geometry, located within the chamber. Purge gas inlets 103, 105 are strategically positioned along one side of the chamber, while exhaust outlets 107, 109 are located on the opposite side. This configuration facilitates a directional gas flow through the wafer surface. To enhance debris management, the upper section 111 of the chamber is tapered, creating a higher pressure zone 119. This pressure gradient allows the purge gas flow in the lower section 113 of the chamber to be directional and efficient, minimizing turbulence and guiding debris 115 toward the exhaust system without interfering with the laser beam path 123.

[0018] Chamber 100 includes a gas flow mechanism that uses an array of nozzles or elongated openings to introduce a laminar or near-laminar gas flow 117 through the wafer. This flow can be calibrated to maintain a velocity range of 0.4 m / s to 1.2 m / s, thereby ensuring effective removal of debris particles from the wafer surface. The gas composition includes inert gases such as nitrogen. The choice of either argon (Ar) or argon (Ar) can enhance the annealing process by preventing unwanted chemical reactions that are expected to occur during the annealing process.

[0019] Debris management is a key aspect of this disclosure, addressing the challenges posed by vaporized particles during laser annealing. When intense laser energy interacts with a wafer, a cloud of debris 115 of carbon nanoparticles and other particles is generated. This system is designed to control this debris and remove it before it interferes with the annealing process or settles on critical surfaces.

[0020] The laminar purge gas flow 117 plays a central role in debris control. By maintaining a consistent and directional flow across the wafer surface, the system ensures that debris particles 115 remain suspended and are effectively transported toward the exhaust outlet 109. This prevents particles from re-landing on the wafer 101 or within the chamber. Additionally, the tapered design of the upper chamber 111 maintains a higher pressure zone 119, which acts as a barrier against debris contamination of the quartz window 121 into which the laser beam is incident. This feature ensures consistent laser delivery 123, reduces maintenance frequency, and extends the operational life of the chamber components. The chamber may include an internal coating to reduce debris adhesion. The quartz window 121 may include an anti-contamination coating.

[0021] This disclosure incorporates a novel method for the interaction between the laser annealing process and the purge gas flow 117. The laser pattern travels in the opposite direction to the laminar gas flow 117. In some embodiments, the galvanometer scanhead can move the beam while the chuck remains stationary. In other embodiments, the chuck can be movable. This ensures that each area of ​​the wafer is annealed on a clean surface because debris generated by earlier laser operations is continuously swept away before the laser reaches subsequent areas.

[0022] This synchronized interaction between the laser pattern 123 and the purge gas flow 117 significantly improves the uniformity and efficiency of the annealing process. By preventing debris clouds 115 from interfering with the laser beam 123, the system ensures consistent energy delivery to the wafer surface 101, resulting in improved annealing outcomes. This method also reduces surface irregularities and improves the overall quality and appearance of the processed wafer. This innovative approach enables the system to achieve uniform annealing very effectively while addressing the common challenge of debris-related contamination.

[0023] While this method and / or system has been described with reference to certain implementations, those skilled in the art will understand that various changes and substitutions can be made without departing from the scope of this method and / or system. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this disclosure without departing from the scope of this disclosure. Therefore, this method and / or system is not intended to be limited to the specific implementations disclosed, but rather will include all implementations falling within the scope of the appended claims.

Claims

1. A method for laser annealing, comprising: In the lower part of the chamber, laminar gas flow is guided through the wafer; A pressure boundary is generated in the upper part of the chamber; as well as Laser annealing is performed in the direction opposite to the laminar gas flow.

2. The method according to claim 1, wherein, The laminar gas flow uses a purge gas, which includes one or more of nitrogen, argon, and an inert gas mixture.

3. The method according to claim 1, wherein, The chamber includes an array of inlet nozzles.

4. The method according to claim 1, wherein, The upper part of the chamber is conical.

5. The method according to claim 1, wherein, The gas flow rate is adjusted according to the wafer size.

6. The method according to claim 1, wherein, The laser annealing uses a laser wavelength that is absorbed by the metal layer.

7. The method according to claim 1, wherein, The pressure in the chamber is maintained below atmospheric level by a vacuum pump.

8. The method according to claim 1, wherein, The pressure boundary prevents particles ranging in size from 0.01 μm to 1.0 μm from entering the upper part of the chamber.

9. The method according to claim 1, wherein, The chamber includes a debris collection system in the emission path.

10. The method according to claim 1, wherein, The laser annealing is configured to minimize energy scattering of the debris cloud.

11. A laser annealing system, comprising: The room comprises a lower chamber section and an upper chamber section; An array of inlet nozzles is configured to generate a laminar gas flow through the wafer; A laser system configured to perform laser annealing on the wafer using a laser pattern traveling in the opposite direction to the laminar gas flow; and The emission system is configured to remove vaporized debris without causing the vaporized debris to redeposit on the wafer.

12. The system according to claim 11, wherein, The purge gas flow velocity can be adjusted between 0.4 m / s and 1.2 m / s.

13. The system according to claim 11, wherein, The laser annealing system includes a vacuum pump configured to maintain a chamber pressure below atmospheric pressure.

14. The system according to claim 11, wherein, The laser system operates at a wavelength optimized for nickel silicide formation.

15. The system according to claim 11, wherein, The emission system includes a debris collection unit.

16. The system according to claim 11, wherein, The chamber includes an internal coating configured to reduce debris adhesion.

17. The system according to claim 11, wherein, The direction of laminar flow is perpendicular to the axis of rotation of the wafer.

18. The system according to claim 11, wherein, The laser pattern can be configured according to the size and material of the wafer.

19. The system according to claim 11, wherein, The laser annealing system includes one or more sensors configured to monitor the uniformity of gas flow.

20. The system according to claim 11, wherein, The room includes quartz windows with an anti-fouling coating.

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