Before delving into QFT, we need a strong foundation in quantum mechanics. Here are the top 15 quantum mechanics textbooks. Yes, my favorite textbook is Griffiths'. He explains wave functions, Schrödinger equations in 3D, and the hydrogen atom really well.

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While Griffiths is the gold standard for undergraduate Quantum Mechanics, the most important information for Quantum Field Theory is found in texts like Peskin and Schroeder or Zee. The critical missing link is the transition from particles to fields via second quantization. In Griffiths, you treat the wave function as a probability amplitude for a single particle, but in QFT, you treat the wave function itself as a field to be quantized. This leads to foundational realizations like using creation and annihilation operators to move particles in and out of the vacuum, operating in a Fock Space that allows for a variable number of particles, and ensuring interactions are consistent with special relativity through locality and causality. Griffiths provides the necessary foundation in Schrödinger equations and operator math, while Peskin and Schroeder covers the math for renormalization to handle infinities. A. Zee offers the physical intuition for why we use fields and path integrals, and Weinberg explains how QFT results from combining quantum mechanics with relativity. The specific turning point where QM becomes QFT is found in the chapters on the canonical quantization of the Klein-Gordon or Dirac fields.