Samsung Electronics Co Ltd v. Sinotechnix LLC

1. Case Identification

• Case #: IPR2025-00332
• Patent #: 7,951,626
• Filed: February 13, 2025
• Petitioner(s): Samsung Electronics Co., Ltd. and Samsung Electronics America, Inc.
• Patent Owner(s): Sinotechnix LLC
• Challenged Claims: 1, 3, 7, 9, 13, and 15

2. Patent Overview

• Title: Method of Manufacturing Light Emitting Device
• Brief Description: The ’626 patent discloses methods for manufacturing a light-emitting device (LED) with sloped side surfaces to improve light extraction efficiency. The methods involve forming a sloped photoresist etching mask and transferring that slope to the underlying semiconductor layers.

3. Grounds for Unpatentability

Ground 1: Claims 1 and 3 are obvious over Eliashevich in view of Rabinzohn

• Prior Art Relied Upon: Eliashevich (WO 2002/059983) and Rabinzohn (Patent 5,378,309).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Eliashevich teaches a method of making an LED with sloped side surfaces by forming a stacked semiconductor structure and using a tapered photoresist mask to etch a mesa. Eliashevich discloses all steps of claim 1 but is vague about how the tapered mask is formed, stating only that it utilizes "controlled processing" techniques "known in the art." Rabinzohn supplies this missing detail by teaching a method of creating a sloped photoresist mask via a "preetching" process, which selectively etches the photoresist to create inclined side surfaces. The combination also allegedly discloses developing the photoresist without a baking process after light exposure, as neither reference teaches such a step. For claim 3, Eliashevich was argued to teach the final step of flip-chip bonding the completed LED structure onto a second substrate.
  • Motivation to Combine: A person of ordinary skill in the art (POSITA), reading Eliashevich's disclosure of using a known "controlled processing" technique, would be motivated to look to other prior art for a specific, suitable method. Rabinzohn provided such a method for the identical purpose of creating a sloped photoresist mask to control an etching profile, making it a natural and logical reference to combine.
  • Expectation of Success: A POSITA would have a reasonable expectation of success because both references operate in the same field of semiconductor fabrication and address the common goal of creating sloped features via etching. Applying Rabinzohn's well-defined preetching method to implement Eliashevich's general "controlled processing" step was presented as a straightforward integration of known techniques.

Ground 2: Claims 9 and 15 are obvious over Eliashevich in view of Rabinzohn and Huang

• Prior Art Relied Upon: Eliashevich (WO 2002/059983), Rabinzohn (Patent 5,378,309), and Huang (Patent 6,444,410).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon the Eliashevich and Rabinzohn combination to meet the different limitations of claim 9, specifically "hard-baking and developing the photoresist" and "etching a side surface of the developed photoresist." Petitioner asserted that Huang teaches conventional photolithography process steps, including both a post-exposure bake (PEB) before development and a hard bake after development. The PEB step taught by Huang (100-120°C) was argued to meet the temperature range for "hard-baking" recited in dependent claim 15 (100-140°C). The combination, therefore, taught hard-baking the photoresist. The "etching" of the developed photoresist's side surface was met by Rabinzohn's preetching step.
  • Motivation to Combine: A POSITA would combine Huang's teachings to improve the standard photolithography process of Eliashevich and Rabinzohn. Hard-baking is a conventional step used to improve photoresist adhesion and smooth its surface profile, which are known benefits that would motivate its inclusion to enhance the overall manufacturing process.
  • Expectation of Success: Integrating Huang's conventional and well-understood baking steps into the photolithography process of the primary combination would be a routine optimization for a POSITA, yielding predictable improvements with a high expectation of success.

Ground 3: Claims 9, 13, and 15 are anticipated by Horio

• Prior Art Relied Upon: Horio (Application # 2005/0281303).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued that Horio discloses every element of claims 9, 13, and 15. Horio teaches a method of manufacturing an LED with a sloped side surface by sequentially forming n-type, luminescent (active), and p-type semiconductor layers on a substrate. It then forms a sloped photoresist mask by exposing, developing, and performing a "post bake" on the photoresist. This post bake, performed at 110-120°C, was asserted to be the claimed "hard-baking" and falls within the temperature range of claim 15. Horio then uses a reactive ion etching (RIE) process that simultaneously etches the sloped side surface of the developed photoresist and transfers the slope to the underlying semiconductor layers. Finally, Horio discloses using a photoresist with a thickness of "approximately 10 μm," which falls within the 3 to 50 μm range required by claim 13.

• Additional Grounds: Petitioner asserted additional obviousness challenges based on Eliashevich, Rabinzohn, and Yoo (for claim 7) and Eliashevich, Rabinzohn, Huang, and Yoo (for claim 13), relying on similar design modification theories.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §314(a) would be inappropriate. The prior art references presented in the petition were never considered during prosecution, weighing against denial under Advanced Bionics. Regarding the Fintiv factors for co-pending district court litigation, Petitioner asserted that the litigation is in its early stages with minimal investment, a trial date is uncertain, and Petitioner will stipulate not to pursue the same invalidity grounds in district court if the IPR is instituted. Petitioner also contended that the strong merits of the unpatentability challenges weigh heavily in favor of institution.

5. Relief Requested

• Petitioner requests institution of inter partes review and cancellation of claims 1, 3, 7, 9, 13, and 15 of the ’626 patent as unpatentable.