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admet prediction, admet, healthcare ai

Predict Absorption Distribution Metabolism Excretion Toxicity.

advanced composition, training techniques

Advanced composition provides tighter privacy bounds than basic composition.

advanced interface bus, aib, advanced packaging

Intel's chiplet interconnect.

advanced mathematics, semiconductor mathematics, lithography mathematics, computational physics, numerical methods

# Advanced Mathematics in Semiconductor Manufacturing ## 1. Lithography & Optical Physics This is arguably the most mathematically demanding area of semiconductor manufacturing. ### 1.1 Fourier Optics & Partial Coherence Theory The foundation of photolithography treats optical imaging as a spatial frequency filtering problem. - **Key Concept**: The mask pattern is decomposed into spatial frequency components - **Optical System**: Acts as a low-pass filter on spatial frequencies - **Hopkins Formulation**: Describes partially coherent imaging The aerial image intensity $I(x,y)$ is given by: $$ I(x,y) = \iint\iint TCC(f_1, g_1, f_2, g_2) \cdot M(f_1, g_1) \cdot M^*(f_2, g_2) \cdot e^{2\pi i[(f_1-f_2)x + (g_1-g_2)y]} \, df_1 \, dg_1 \, df_2 \, dg_2 $$ Where: - $TCC$ = Transmission Cross-Coefficient - $M(f,g)$ = Mask spectrum (Fourier transform of mask pattern) - $M^*$ = Complex conjugate of mask spectrum **SOCS Decomposition** (Sum of Coherent Systems): $$ TCC(f_1, g_1, f_2, g_2) = \sum_{k=1}^{N} \lambda_k \phi_k(f_1, g_1) \phi_k^*(f_2, g_2) $$ - Eigenvalue decomposition makes computation tractable - $\lambda_k$ are eigenvalues (typically only 10-20 terms needed) - $\phi_k$ are eigenfunctions ### 1.2 Inverse Lithography Technology (ILT) Given a desired wafer pattern $T(x,y)$, find the optimal mask $M(x,y)$. **Mathematical Framework**: - **Objective Function**: $$ \min_{M} \left\| I[M](x,y) - T(x,y) \right\|^2 + \alpha R[M] $$ - **Key Methods**: - Variational calculus and gradient descent in function spaces - Level-set methods for topology optimization: $$ \frac{\partial \phi}{\partial t} + v|\nabla\phi| = 0 $$ - Tikhonov regularization: $R[M] = \|\nabla M\|^2$ - Total-variation regularization: $R[M] = \int |\nabla M| \, dx \, dy$ - Adjoint methods for efficient gradient computation ### 1.3 EUV & Rigorous Electromagnetics At $\lambda = 13.5$ nm, scalar diffraction theory fails. Full vector Maxwell's equations are required. **Maxwell's Equations** (time-harmonic form): $$ \nabla \times \mathbf{E} = -i\omega\mu\mathbf{H} $$ $$ \nabla \times \mathbf{H} = i\omega\varepsilon\mathbf{E} $$ **Numerical Methods**: - **RCWA** (Rigorous Coupled-Wave Analysis): - Eigenvalue problem for each diffraction order - Transfer matrix for multilayer stacks: $$ \begin{pmatrix} E^+ \\ E^- \end{pmatrix}_{out} = \mathbf{T} \begin{pmatrix} E^+ \\ E^- \end{pmatrix}_{in} $$ - **FDTD** (Finite-Difference Time-Domain): - Yee grid discretization - Leapfrog time integration: $$ E^{n+1} = E^n + \frac{\Delta t}{\varepsilon} \nabla \times H^{n+1/2} $$ - **Multilayer Thin-Film Optics**: - Fresnel coefficients at each interface - Transfer matrix method for $N$ layers ### 1.4 Aberration Theory Optical aberrations characterized using **Zernike Polynomials**: $$ W(\rho, \theta) = \sum_{n,m} Z_n^m R_n^m(\rho) \cdot \begin{cases} \cos(m\theta) & \text{(even)} \\ \sin(m\theta) & \text{(odd)} \end{cases} $$ Where $R_n^m(\rho)$ are radial polynomials: $$ R_n^m(\rho) = \sum_{k=0}^{(n-m)/2} \frac{(-1)^k (n-k)!}{k! \left(\frac{n+m}{2}-k\right)! \left(\frac{n-m}{2}-k\right)!} \rho^{n-2k} $$ **Common Aberrations**: | Zernike Term | Name | Effect | |--------------|------|--------| | $Z_4^0$ | Defocus | Uniform blur | | $Z_3^1$ | Coma | Asymmetric distortion | | $Z_4^0$ | Spherical | Halo effect | | $Z_2^2$ | Astigmatism | Directional blur | ## 2. Quantum Mechanics & Device Physics As transistors reach sub-5nm dimensions, classical models break down. ### 2.1 Schrödinger Equation & Quantum Transport **Time-Independent Schrödinger Equation**: $$ \hat{H}\psi = E\psi $$ $$ \left[-\frac{\hbar^2}{2m}\nabla^2 + V(\mathbf{r})\right]\psi(\mathbf{r}) = E\psi(\mathbf{r}) $$ **Non-Equilibrium Green's Function (NEGF) Formalism**: - Retarded Green's function: $$ G^R(E) = \left[(E + i\eta)I - H - \Sigma_L - \Sigma_R\right]^{-1} $$ - Self-energy $\Sigma$ incorporates: - Contact coupling - Scattering mechanisms - Electron-phonon interaction - Current calculation: $$ I = \frac{2e}{h} \int T(E) [f_L(E) - f_R(E)] \, dE $$ - Transmission function: $$ T(E) = \text{Tr}\left[\Gamma_L G^R \Gamma_R G^A\right] $$ **Wigner Function** (bridging quantum and semiclassical): $$ W(x,p) = \frac{1}{2\pi\hbar} \int \psi^*\left(x + \frac{y}{2}\right) \psi\left(x - \frac{y}{2}\right) e^{ipy/\hbar} \, dy $$ ### 2.2 Band Structure Theory **$k \cdot p$ Perturbation Theory**: $$ H_{k \cdot p} = \frac{p^2}{2m_0} + V(\mathbf{r}) + \frac{\hbar}{m_0}\mathbf{k} \cdot \mathbf{p} + \frac{\hbar^2 k^2}{2m_0} $$ **Effective Mass Tensor**: $$ \frac{1}{m^*_{ij}} = \frac{1}{\hbar^2} \frac{\partial^2 E}{\partial k_i \partial k_j} $$ **Tight-Binding Hamiltonian**: $$ H = \sum_i \varepsilon_i |i\rangle\langle i| + \sum_{\langle i,j \rangle} t_{ij} |i\rangle\langle j| $$ - $\varepsilon_i$ = on-site energy - $t_{ij}$ = hopping integral (Slater-Koster parameters) ### 2.3 Semiclassical Transport **Boltzmann Transport Equation**: $$ \frac{\partial f}{\partial t} + \mathbf{v} \cdot \nabla_r f + \frac{\mathbf{F}}{\hbar} \cdot \nabla_k f = \left(\frac{\partial f}{\partial t}\right)_{coll} $$ - 6D phase space $(x, y, z, k_x, k_y, k_z)$ - Collision integral (scattering): $$ \left(\frac{\partial f}{\partial t}\right)_{coll} = \sum_{k'} [S(k',k)f(k')(1-f(k)) - S(k,k')f(k)(1-f(k'))] $$ **Drift-Diffusion Equations** (moment expansion): $$ \mathbf{J}_n = q\mu_n n\mathbf{E} + qD_n\nabla n $$ $$ \mathbf{J}_p = q\mu_p p\mathbf{E} - qD_p\nabla p $$ ## 3. Process Simulation PDEs ### 3.1 Dopant Diffusion **Fick's Second Law** (concentration-dependent): $$ \frac{\partial C}{\partial t} = \nabla \cdot (D(C,T) \nabla C) + G - R $$ **Coupled Point-Defect System**: $$ \begin{aligned} \frac{\partial C_A}{\partial t} &= \nabla \cdot (D_A \nabla C_A) + k_{AI}C_AC_I - k_{AV}C_AC_V \\ \frac{\partial C_I}{\partial t} &= \nabla \cdot (D_I \nabla C_I) + G_I - k_{IV}C_IC_V \\ \frac{\partial C_V}{\partial t} &= \nabla \cdot (D_V \nabla C_V) + G_V - k_{IV}C_IC_V \end{aligned} $$ Where: - $C_A$ = dopant concentration - $C_I$ = interstitial concentration - $C_V$ = vacancy concentration - $k_{ij}$ = reaction rate constants ### 3.2 Oxidation & Film Growth **Deal-Grove Model**: $$ x_{ox}^2 + Ax_{ox} = B(t + \tau) $$ - $A$ = linear rate constant (surface reaction limited) - $B$ = parabolic rate constant (diffusion limited) - $\tau$ = time offset for initial oxide **Moving Boundary (Stefan) Problem**: $$ D\frac{\partial C}{\partial x}\bigg|_{x=s(t)} = C^* \frac{ds}{dt} $$ ### 3.3 Ion Implantation **Binary Collision Approximation** (Monte Carlo): - Screened Coulomb potential: $$ V(r) = \frac{Z_1 Z_2 e^2}{r} \phi\left(\frac{r}{a}\right) $$ - Scattering angle from two-body collision integral **As-Implanted Profile** (Pearson IV distribution): $$ f(x) = f_0 \left[1 + \left(\frac{x-R_p}{b}\right)^2\right]^{-m} \exp\left[-r \tan^{-1}\left(\frac{x-R_p}{b}\right)\right] $$ Parameters: $R_p$ (projected range), $\Delta R_p$ (straggle), skewness, kurtosis ### 3.4 Plasma Etching **Electron Energy Distribution** (Boltzmann equation): $$ \frac{\partial f}{\partial t} + \mathbf{v} \cdot \nabla f - \frac{e\mathbf{E}}{m} \cdot \nabla_v f = C[f] $$ **Child-Langmuir Law** (sheath ion flux): $$ J = \frac{4\varepsilon_0}{9} \sqrt{\frac{2e}{M}} \frac{V^{3/2}}{d^2} $$ ### 3.5 Chemical-Mechanical Polishing (CMP) **Preston Equation**: $$ \frac{dh}{dt} = K_p \cdot P \cdot V $$ - $K_p$ = Preston coefficient - $P$ = local pressure - $V$ = relative velocity **Pattern-Density Dependent Model**: $$ P_{local} = P_{avg} \cdot \frac{A_{total}}{A_{contact}(\rho)} $$ ## 4. Electromagnetic Simulation ### 4.1 Interconnect Modeling **Capacitance Extraction** (Laplace equation): $$ \nabla^2 \phi = 0 \quad \text{(dielectric regions)} $$ $$ \nabla \cdot (\varepsilon \nabla \phi) = -\rho \quad \text{(with charges)} $$ **Boundary Element Method**: $$ c(\mathbf{r})\phi(\mathbf{r}) = \int_S \left[\phi(\mathbf{r}') \frac{\partial G}{\partial n'} - G(\mathbf{r}, \mathbf{r}') \frac{\partial \phi}{\partial n'}\right] dS' $$ Where $G(\mathbf{r}, \mathbf{r}') = \frac{1}{4\pi|\mathbf{r} - \mathbf{r}'|}$ (free-space Green's function) ### 4.2 Partial Inductance **PEEC Method** (Partial Element Equivalent Circuit): $$ L_{p,ij} = \frac{\mu_0}{4\pi} \frac{1}{a_i a_j} \int_{V_i} \int_{V_j} \frac{d\mathbf{l}_i \cdot d\mathbf{l}_j}{|\mathbf{r}_i - \mathbf{r}_j|} $$ ## 5. Statistical & Stochastic Methods ### 5.1 Process Variability **Multivariate Gaussian Model**: $$ p(\mathbf{x}) = \frac{1}{(2\pi)^{n/2}|\Sigma|^{1/2}} \exp\left(-\frac{1}{2}(\mathbf{x}-\boldsymbol{\mu})^T \Sigma^{-1} (\mathbf{x}-\boldsymbol{\mu})\right) $$ **Principal Component Analysis**: $$ \mathbf{X} = \mathbf{U}\mathbf{S}\mathbf{V}^T $$ - Transform to uncorrelated variables - Dimensionality reduction: retain components with largest singular values **Polynomial Chaos Expansion**: $$ Y(\boldsymbol{\xi}) = \sum_{k=0}^{P} y_k \Psi_k(\boldsymbol{\xi}) $$ - $\Psi_k$ = orthogonal polynomial basis (Hermite for Gaussian inputs) - Enables uncertainty quantification without Monte Carlo ### 5.2 Yield Modeling **Poisson Defect Model**: $$ Y = e^{-D \cdot A} $$ - $D$ = defect density (defects/cm²) - $A$ = critical area **Negative Binomial** (clustered defects): $$ Y = \left(1 + \frac{DA}{\alpha}\right)^{-\alpha} $$ ### 5.3 Reliability Physics **Weibull Distribution** (lifetime): $$ F(t) = 1 - \exp\left[-\left(\frac{t}{\eta}\right)^\beta\right] $$ - $\eta$ = scale parameter (characteristic life) - $\beta$ = shape parameter (failure mode indicator) **Black's Equation** (electromigration): $$ MTTF = A \cdot J^{-n} \cdot \exp\left(\frac{E_a}{k_B T}\right) $$ ## 6. Optimization & Inverse Problems ### 6.1 Design of Experiments **Response Surface Methodology**: $$ y = \beta_0 + \sum_i \beta_i x_i + \sum_i \beta_{ii} x_i^2 + \sum_{i E_g \\ 0 & E \leq E_g \end{cases} $$ ## 7. Computational Geometry & Graph Theory ### 7.1 VLSI Physical Design **Graph Partitioning** (min-cut): $$ \min_{P} \sum_{(u,v) \in E : u \in P, v \notin P} w(u,v) $$ - Kernighan-Lin algorithm - Spectral methods using Fiedler vector **Placement** (quadratic programming): $$ \min_{\mathbf{x}, \mathbf{y}} \sum_{(i,j) \in E} w_{ij} \left[(x_i - x_j)^2 + (y_i - y_j)^2\right] $$ **Steiner Tree Problem** (routing): - Given pins to connect, find minimum-length tree - NP-hard; use approximation algorithms (RSMT, rectilinear Steiner) ### 7.2 Mask Data Preparation - **Boolean Operations**: Union, intersection, difference of polygons - **Polygon Clipping**: Sutherland-Hodgman, Vatti algorithms - **Fracturing**: Decompose complex shapes into trapezoids for e-beam writing ## 8. Thermal & Mechanical Analysis ### 8.1 Heat Transport **Fourier Heat Equation**: $$ \rho c_p \frac{\partial T}{\partial t} = \nabla \cdot (k \nabla T) + Q $$ **Phonon Boltzmann Transport** (nanoscale): $$ \frac{\partial f}{\partial t} + \mathbf{v}_g \cdot \nabla f = \frac{f_0 - f}{\tau} $$ - Required when feature size $<$ phonon mean free path - Non-Fourier effects: ballistic transport, thermal rectification ### 8.2 Thermo-Mechanical Stress **Linear Elasticity**: $$ \sigma_{ij} = C_{ijkl} \varepsilon_{kl} $$ **Equilibrium**: $$ \nabla \cdot \boldsymbol{\sigma} + \mathbf{f} = 0 $$ **Thin Film Stress** (Stoney Equation): $$ \sigma_f = \frac{E_s h_s^2}{6(1-\nu_s) h_f} \cdot \frac{1}{R} $$ - $R$ = wafer curvature radius - $h_s$, $h_f$ = substrate and film thickness **Thermal Stress**: $$ \varepsilon_{thermal} = \alpha \Delta T $$ $$ \sigma_{thermal} = E(\alpha_{film} - \alpha_{substrate})\Delta T $$ ## 9. Multiscale & Atomistic Methods ### 9.1 Molecular Dynamics **Equation of Motion**: $$ m_i \frac{d^2 \mathbf{r}_i}{dt^2} = -\nabla_i U(\{\mathbf{r}\}) $$ **Interatomic Potentials**: - **Tersoff** (covalent, e.g., Si): $$ V_{ij} = f_c(r_{ij})[f_R(r_{ij}) + b_{ij} f_A(r_{ij})] $$ - **Embedded Atom Method** (metals): $$ E_i = F_i(\rho_i) + \frac{1}{2}\sum_{j \neq i} \phi_{ij}(r_{ij}) $$ **Velocity Verlet Integration**: $$ \mathbf{r}(t+\Delta t) = \mathbf{r}(t) + \mathbf{v}(t)\Delta t + \frac{\mathbf{a}(t)}{2}\Delta t^2 $$ $$ \mathbf{v}(t+\Delta t) = \mathbf{v}(t) + \frac{\mathbf{a}(t) + \mathbf{a}(t+\Delta t)}{2}\Delta t $$ ### 9.2 Kinetic Monte Carlo **Master Equation**: $$ \frac{dP_i}{dt} = \sum_j (W_{ji} P_j - W_{ij} P_i) $$ **Transition Rates** (Arrhenius): $$ W_{ij} = \nu_0 \exp\left(-\frac{E_a}{k_B T}\right) $$ **BKL Algorithm**: 1. Compute all rates $\{r_i\}$ 2. Total rate: $R = \sum_i r_i$ 3. Select event $j$ with probability $r_j / R$ 4. Advance time: $\Delta t = -\ln(u) / R$ where $u \in (0,1)$ ### 9.3 Ab Initio Methods **Kohn-Sham Equations** (DFT): $$ \left[-\frac{\hbar^2}{2m}\nabla^2 + V_{eff}(\mathbf{r})\right]\psi_i(\mathbf{r}) = \varepsilon_i \psi_i(\mathbf{r}) $$ $$ V_{eff} = V_{ext} + V_H[n] + V_{xc}[n] $$ Where: - $V_H[n] = \int \frac{n(\mathbf{r}')}{|\mathbf{r} - \mathbf{r}'|} d\mathbf{r}'$ (Hartree potential) - $V_{xc}[n] = \frac{\delta E_{xc}[n]}{\delta n}$ (exchange-correlation) ## 10. Machine Learning & Data Science ### 10.1 Virtual Metrology **Regression Models**: - Linear: $y = \mathbf{w}^T \mathbf{x} + b$ - Kernel Ridge Regression: $$ \mathbf{w} = (\mathbf{K} + \lambda \mathbf{I})^{-1} \mathbf{y} $$ - Neural Networks: $y = f_L \circ f_{L-1} \circ \cdots \circ f_1(\mathbf{x})$ ### 10.2 Defect Detection **Convolutional Neural Networks**: $$ (f * g)[n] = \sum_m f[m] \cdot g[n-m] $$ - Feature extraction through learned filters - Pooling for translation invariance **Anomaly Detection**: - Autoencoders: $\text{loss} = \|x - D(E(x))\|^2$ - Isolation Forest: anomaly score based on path length ### 10.3 Process Optimization **Bayesian Optimization**: $$ x_{next} = \arg\max_x \alpha(x | \mathcal{D}) $$ **Acquisition Functions**: - Expected Improvement: $\alpha_{EI}(x) = \mathbb{E}[\max(f(x) - f^*, 0)]$ - Upper Confidence Bound: $\alpha_{UCB}(x) = \mu(x) + \kappa \sigma(x)$ ## Summary | Domain | Key Mathematical Topics | |--------|-------------------------| | **Lithography** | Fourier analysis, inverse problems, PDEs, optimization | | **Device Physics** | Quantum mechanics, functional analysis, group theory | | **Process Simulation** | Nonlinear PDEs, Monte Carlo, stochastic processes | | **Metrology** | Inverse problems, electromagnetics, statistical inference | | **Yield/Reliability** | Probability theory, extreme value statistics | | **Physical Design** | Graph theory, combinatorial optimization, ILP | | **Thermal/Mechanical** | Continuum mechanics, FEM, tensor analysis | | **Atomistic Modeling** | Statistical mechanics, DFT, stochastic simulation | | **Machine Learning** | Neural networks, Bayesian inference, optimization |

advanced node thermal, thermal management

Advanced nodes face elevated thermal challenges from increased power density and reduced thermal conductivity.

advanced ocv (aocv),advanced ocv,aocv,design

Statistical OCV modeling.

advanced oxidation, environmental & sustainability

Advanced oxidation processes generate hydroxyl radicals degrading persistent organic pollutants.

advanced patterning beol, process integration

Advanced patterning techniques enable metal pitch scaling through SADP SAQP or EUV lithography.

advanced process control implementation, apc, process control

Deploy control algorithms in production.

advanced topics, advanced mathematics, semiconductor mathematics, lithography math, plasma physics, diffusion math

# Semiconductor Manufacturing: Advanced Mathematics ## 1. Lithography & Optical Physics This is arguably the most mathematically demanding area of semiconductor manufacturing. ### 1.1 Fourier Optics & Partial Coherence Theory The foundation of photolithography treats optical imaging as a spatial frequency filtering problem. - **Key Concept**: The mask pattern is decomposed into spatial frequency components - **Optical System**: Acts as a low-pass filter on spatial frequencies - **Hopkins Formulation**: Describes partially coherent imaging The aerial image intensity $I(x,y)$ is given by: $$ I(x,y) = \iint\iint TCC(f_1, g_1, f_2, g_2) \cdot M(f_1, g_1) \cdot M^*(f_2, g_2) \cdot e^{2\pi i[(f_1-f_2)x + (g_1-g_2)y]} \, df_1 \, dg_1 \, df_2 \, dg_2 $$ Where: - $TCC$ = Transmission Cross-Coefficient - $M(f,g)$ = Mask spectrum (Fourier transform of mask pattern) - $M^*$ = Complex conjugate of mask spectrum **SOCS Decomposition** (Sum of Coherent Systems): $$ TCC(f_1, g_1, f_2, g_2) = \sum_{k=1}^{N} \lambda_k \phi_k(f_1, g_1) \phi_k^*(f_2, g_2) $$ - Eigenvalue decomposition makes computation tractable - $\lambda_k$ are eigenvalues (typically only 10-20 terms needed) - $\phi_k$ are eigenfunctions ### 1.2 Inverse Lithography Technology (ILT) Given a desired wafer pattern $T(x,y)$, find the optimal mask $M(x,y)$. **Mathematical Framework**: - **Objective Function**: $$ \min_{M} \left\| I[M](x,y) - T(x,y) \right\|^2 + \alpha R[M] $$ - **Key Methods**: - Variational calculus and gradient descent in function spaces - Level-set methods for topology optimization: $$ \frac{\partial \phi}{\partial t} + v|\nabla\phi| = 0 $$ - Tikhonov regularization: $R[M] = \|\nabla M\|^2$ - Total-variation regularization: $R[M] = \int |\nabla M| \, dx \, dy$ - Adjoint methods for efficient gradient computation ### 1.3 EUV & Rigorous Electromagnetics At $\lambda = 13.5$ nm, scalar diffraction theory fails. Full vector Maxwell's equations are required. **Maxwell's Equations** (time-harmonic form): $$ \nabla \times \mathbf{E} = -i\omega\mu\mathbf{H} $$ $$ \nabla \times \mathbf{H} = i\omega\varepsilon\mathbf{E} $$ **Numerical Methods**: - **RCWA** (Rigorous Coupled-Wave Analysis): - Eigenvalue problem for each diffraction order - Transfer matrix for multilayer stacks: $$ \begin{pmatrix} E^+ \\ E^- \end{pmatrix}_{out} = \mathbf{T} \begin{pmatrix} E^+ \\ E^- \end{pmatrix}_{in} $$ - **FDTD** (Finite-Difference Time-Domain): - Yee grid discretization - Leapfrog time integration: $$ E^{n+1} = E^n + \frac{\Delta t}{\varepsilon} \nabla \times H^{n+1/2} $$ - **Multilayer Thin-Film Optics**: - Fresnel coefficients at each interface - Transfer matrix method for $N$ layers ### 1.4 Aberration Theory Optical aberrations characterized using **Zernike Polynomials**: $$ W(\rho, \theta) = \sum_{n,m} Z_n^m R_n^m(\rho) \cdot \begin{cases} \cos(m\theta) & \text{(even)} \\ \sin(m\theta) & \text{(odd)} \end{cases} $$ Where $R_n^m(\rho)$ are radial polynomials: $$ R_n^m(\rho) = \sum_{k=0}^{(n-m)/2} \frac{(-1)^k (n-k)!}{k! \left(\frac{n+m}{2}-k\right)! \left(\frac{n-m}{2}-k\right)!} \rho^{n-2k} $$ **Common Aberrations**: | Zernike Term | Name | Effect | |--------------|------|--------| | $Z_4^0$ | Defocus | Uniform blur | | $Z_3^1$ | Coma | Asymmetric distortion | | $Z_4^0$ | Spherical | Halo effect | | $Z_2^2$ | Astigmatism | Directional blur | ## 2. Quantum Mechanics & Device Physics As transistors reach sub-5nm dimensions, classical models break down. ### 2.1 Schrödinger Equation & Quantum Transport **Time-Independent Schrödinger Equation**: $$ \hat{H}\psi = E\psi $$ $$ \left[-\frac{\hbar^2}{2m}\nabla^2 + V(\mathbf{r})\right]\psi(\mathbf{r}) = E\psi(\mathbf{r}) $$ **Non-Equilibrium Green's Function (NEGF) Formalism**: - Retarded Green's function: $$ G^R(E) = \left[(E + i\eta)I - H - \Sigma_L - \Sigma_R\right]^{-1} $$ - Self-energy $\Sigma$ incorporates: - Contact coupling - Scattering mechanisms - Electron-phonon interaction - Current calculation: $$ I = \frac{2e}{h} \int T(E) [f_L(E) - f_R(E)] \, dE $$ - Transmission function: $$ T(E) = \text{Tr}\left[\Gamma_L G^R \Gamma_R G^A\right] $$ **Wigner Function** (bridging quantum and semiclassical): $$ W(x,p) = \frac{1}{2\pi\hbar} \int \psi^*\left(x + \frac{y}{2}\right) \psi\left(x - \frac{y}{2}\right) e^{ipy/\hbar} \, dy $$ ### 2.2 Band Structure Theory **k·p Perturbation Theory**: $$ H_{k \cdot p} = \frac{p^2}{2m_0} + V(\mathbf{r}) + \frac{\hbar}{m_0}\mathbf{k} \cdot \mathbf{p} + \frac{\hbar^2 k^2}{2m_0} $$ **Effective Mass Tensor**: $$ \frac{1}{m^*_{ij}} = \frac{1}{\hbar^2} \frac{\partial^2 E}{\partial k_i \partial k_j} $$ **Tight-Binding Hamiltonian**: $$ H = \sum_i \varepsilon_i |i\rangle\langle i| + \sum_{\langle i,j \rangle} t_{ij} |i\rangle\langle j| $$ - $\varepsilon_i$ = on-site energy - $t_{ij}$ = hopping integral (Slater-Koster parameters) ### 2.3 Semiclassical Transport **Boltzmann Transport Equation**: $$ \frac{\partial f}{\partial t} + \mathbf{v} \cdot \nabla_r f + \frac{\mathbf{F}}{\hbar} \cdot \nabla_k f = \left(\frac{\partial f}{\partial t}\right)_{coll} $$ - 6D phase space $(x, y, z, k_x, k_y, k_z)$ - Collision integral (scattering): $$ \left(\frac{\partial f}{\partial t}\right)_{coll} = \sum_{k'} [S(k',k)f(k')(1-f(k)) - S(k,k')f(k)(1-f(k'))] $$ **Drift-Diffusion Equations** (moment expansion): $$ \mathbf{J}_n = q\mu_n n\mathbf{E} + qD_n\nabla n $$ $$ \mathbf{J}_p = q\mu_p p\mathbf{E} - qD_p\nabla p $$ ## 3. Process Simulation PDEs ### 3.1 Dopant Diffusion **Fick's Second Law** (concentration-dependent): $$ \frac{\partial C}{\partial t} = \nabla \cdot (D(C,T) \nabla C) + G - R $$ **Coupled Point-Defect System**: $$ \begin{aligned} \frac{\partial C_A}{\partial t} &= \nabla \cdot (D_A \nabla C_A) + k_{AI}C_AC_I - k_{AV}C_AC_V \\ \frac{\partial C_I}{\partial t} &= \nabla \cdot (D_I \nabla C_I) + G_I - k_{IV}C_IC_V \\ \frac{\partial C_V}{\partial t} &= \nabla \cdot (D_V \nabla C_V) + G_V - k_{IV}C_IC_V \end{aligned} $$ Where: - $C_A$ = dopant concentration - $C_I$ = interstitial concentration - $C_V$ = vacancy concentration - $k_{ij}$ = reaction rate constants ### 3.2 Oxidation & Film Growth **Deal-Grove Model**: $$ x_{ox}^2 + Ax_{ox} = B(t + \tau) $$ - $A$ = linear rate constant (surface reaction limited) - $B$ = parabolic rate constant (diffusion limited) - $\tau$ = time offset for initial oxide **Moving Boundary (Stefan) Problem**: $$ D\frac{\partial C}{\partial x}\bigg|_{x=s(t)} = C^* \frac{ds}{dt} $$ ### 3.3 Ion Implantation **Binary Collision Approximation** (Monte Carlo): - Screened Coulomb potential: $$ V(r) = \frac{Z_1 Z_2 e^2}{r} \phi\left(\frac{r}{a}\right) $$ - Scattering angle from two-body collision integral **As-Implanted Profile** (Pearson IV distribution): $$ f(x) = f_0 \left[1 + \left(\frac{x-R_p}{b}\right)^2\right]^{-m} \exp\left[-r \tan^{-1}\left(\frac{x-R_p}{b}\right)\right] $$ Parameters: $R_p$ (projected range), $\Delta R_p$ (straggle), skewness, kurtosis ### 3.4 Plasma Etching **Electron Energy Distribution** (Boltzmann equation): $$ \frac{\partial f}{\partial t} + \mathbf{v} \cdot \nabla f - \frac{e\mathbf{E}}{m} \cdot \nabla_v f = C[f] $$ **Child-Langmuir Law** (sheath ion flux): $$ J = \frac{4\varepsilon_0}{9} \sqrt{\frac{2e}{M}} \frac{V^{3/2}}{d^2} $$ ### 3.5 Chemical-Mechanical Polishing (CMP) **Preston Equation**: $$ \frac{dh}{dt} = K_p \cdot P \cdot V $$ - $K_p$ = Preston coefficient - $P$ = local pressure - $V$ = relative velocity **Pattern-Density Dependent Model**: $$ P_{local} = P_{avg} \cdot \frac{A_{total}}{A_{contact}(\rho)} $$ ## 4. Electromagnetic Simulation ### 4.1 Interconnect Modeling **Capacitance Extraction** (Laplace equation): $$ \nabla^2 \phi = 0 \quad \text{(dielectric regions)} $$ $$ \nabla \cdot (\varepsilon \nabla \phi) = -\rho \quad \text{(with charges)} $$ **Boundary Element Method**: $$ c(\mathbf{r})\phi(\mathbf{r}) = \int_S \left[\phi(\mathbf{r}') \frac{\partial G}{\partial n'} - G(\mathbf{r}, \mathbf{r}') \frac{\partial \phi}{\partial n'}\right] dS' $$ Where $G(\mathbf{r}, \mathbf{r}') = \frac{1}{4\pi|\mathbf{r} - \mathbf{r}'|}$ (free-space Green's function) ### 4.2 Partial Inductance **PEEC Method** (Partial Element Equivalent Circuit): $$ L_{p,ij} = \frac{\mu_0}{4\pi} \frac{1}{a_i a_j} \int_{V_i} \int_{V_j} \frac{d\mathbf{l}_i \cdot d\mathbf{l}_j}{|\mathbf{r}_i - \mathbf{r}_j|} $$ ## 5. Statistical & Stochastic Methods ### 5.1 Process Variability **Multivariate Gaussian Model**: $$ p(\mathbf{x}) = \frac{1}{(2\pi)^{n/2}|\Sigma|^{1/2}} \exp\left(-\frac{1}{2}(\mathbf{x}-\boldsymbol{\mu})^T \Sigma^{-1} (\mathbf{x}-\boldsymbol{\mu})\right) $$ **Principal Component Analysis**: $$ \mathbf{X} = \mathbf{U}\mathbf{S}\mathbf{V}^T $$ - Transform to uncorrelated variables - Dimensionality reduction: retain components with largest singular values **Polynomial Chaos Expansion**: $$ Y(\boldsymbol{\xi}) = \sum_{k=0}^{P} y_k \Psi_k(\boldsymbol{\xi}) $$ - $\Psi_k$ = orthogonal polynomial basis (Hermite for Gaussian inputs) - Enables uncertainty quantification without Monte Carlo ### 5.2 Yield Modeling **Poisson Defect Model**: $$ Y = e^{-D \cdot A} $$ - $D$ = defect density (defects/cm²) - $A$ = critical area **Negative Binomial** (clustered defects): $$ Y = \left(1 + \frac{DA}{\alpha}\right)^{-\alpha} $$ ### 5.3 Reliability Physics **Weibull Distribution** (lifetime): $$ F(t) = 1 - \exp\left[-\left(\frac{t}{\eta}\right)^\beta\right] $$ - $\eta$ = scale parameter (characteristic life) - $\beta$ = shape parameter (failure mode indicator) **Black's Equation** (electromigration): $$ MTTF = A \cdot J^{-n} \cdot \exp\left(\frac{E_a}{k_B T}\right) $$ ## 6. Optimization & Inverse Problems ### 6.1 Design of Experiments **Response Surface Methodology**: $$ y = \beta_0 + \sum_i \beta_i x_i + \sum_i \beta_{ii} x_i^2 + \sum_{i E_g \\ 0 & E \leq E_g \end{cases} $$ ## 7. Computational Geometry & Graph Theory ### 7.1 VLSI Physical Design **Graph Partitioning** (min-cut): $$ \min_{P} \sum_{(u,v) \in E : u \in P, v \notin P} w(u,v) $$ - Kernighan-Lin algorithm - Spectral methods using Fiedler vector **Placement** (quadratic programming): $$ \min_{\mathbf{x}, \mathbf{y}} \sum_{(i,j) \in E} w_{ij} \left[(x_i - x_j)^2 + (y_i - y_j)^2\right] $$ **Steiner Tree Problem** (routing): - Given pins to connect, find minimum-length tree - NP-hard; use approximation algorithms (RSMT, rectilinear Steiner) ### 7.2 Mask Data Preparation - **Boolean Operations**: Union, intersection, difference of polygons - **Polygon Clipping**: Sutherland-Hodgman, Vatti algorithms - **Fracturing**: Decompose complex shapes into trapezoids for e-beam writing ## 8. Thermal & Mechanical Analysis ### 8.1 Heat Transport **Fourier Heat Equation**: $$ \rho c_p \frac{\partial T}{\partial t} = \nabla \cdot (k \nabla T) + Q $$ **Phonon Boltzmann Transport** (nanoscale): $$ \frac{\partial f}{\partial t} + \mathbf{v}_g \cdot \nabla f = \frac{f_0 - f}{\tau} $$ - Required when feature size $<$ phonon mean free path - Non-Fourier effects: ballistic transport, thermal rectification ### 8.2 Thermo-Mechanical Stress **Linear Elasticity**: $$ \sigma_{ij} = C_{ijkl} \varepsilon_{kl} $$ **Equilibrium**: $$ \nabla \cdot \boldsymbol{\sigma} + \mathbf{f} = 0 $$ **Thin Film Stress** (Stoney Equation): $$ \sigma_f = \frac{E_s h_s^2}{6(1-\nu_s) h_f} \cdot \frac{1}{R} $$ - $R$ = wafer curvature radius - $h_s$, $h_f$ = substrate and film thickness **Thermal Stress**: $$ \varepsilon_{thermal} = \alpha \Delta T $$ $$ \sigma_{thermal} = E(\alpha_{film} - \alpha_{substrate})\Delta T $$ ## 9. Multiscale & Atomistic Methods ### 9.1 Molecular Dynamics **Equation of Motion**: $$ m_i \frac{d^2 \mathbf{r}_i}{dt^2} = -\nabla_i U(\{\mathbf{r}\}) $$ **Interatomic Potentials**: - **Tersoff** (covalent, e.g., Si): $$ V_{ij} = f_c(r_{ij})[f_R(r_{ij}) + b_{ij} f_A(r_{ij})] $$ - **Embedded Atom Method** (metals): $$ E_i = F_i(\rho_i) + \frac{1}{2}\sum_{j \neq i} \phi_{ij}(r_{ij}) $$ **Velocity Verlet Integration**: $$ \mathbf{r}(t+\Delta t) = \mathbf{r}(t) + \mathbf{v}(t)\Delta t + \frac{\mathbf{a}(t)}{2}\Delta t^2 $$ $$ \mathbf{v}(t+\Delta t) = \mathbf{v}(t) + \frac{\mathbf{a}(t) + \mathbf{a}(t+\Delta t)}{2}\Delta t $$ ### 9.2 Kinetic Monte Carlo **Master Equation**: $$ \frac{dP_i}{dt} = \sum_j (W_{ji} P_j - W_{ij} P_i) $$ **Transition Rates** (Arrhenius): $$ W_{ij} = \nu_0 \exp\left(-\frac{E_a}{k_B T}\right) $$ **BKL Algorithm**: 1. Compute all rates $\{r_i\}$ 2. Total rate: $R = \sum_i r_i$ 3. Select event $j$ with probability $r_j / R$ 4. Advance time: $\Delta t = -\ln(u) / R$ where $u \in (0,1)$ ### 9.3 Ab Initio Methods **Kohn-Sham Equations** (DFT): $$ \left[-\frac{\hbar^2}{2m}\nabla^2 + V_{eff}(\mathbf{r})\right]\psi_i(\mathbf{r}) = \varepsilon_i \psi_i(\mathbf{r}) $$ $$ V_{eff} = V_{ext} + V_H[n] + V_{xc}[n] $$ Where: - $V_H[n] = \int \frac{n(\mathbf{r}')}{|\mathbf{r} - \mathbf{r}'|} d\mathbf{r}'$ (Hartree potential) - $V_{xc}[n] = \frac{\delta E_{xc}[n]}{\delta n}$ (exchange-correlation) ## 10. Machine Learning & Data Science ### 10.1 Virtual Metrology **Regression Models**: - Linear: $y = \mathbf{w}^T \mathbf{x} + b$ - Kernel Ridge Regression: $$ \mathbf{w} = (\mathbf{K} + \lambda \mathbf{I})^{-1} \mathbf{y} $$ - Neural Networks: $y = f_L \circ f_{L-1} \circ \cdots \circ f_1(\mathbf{x})$ ### 10.2 Defect Detection **Convolutional Neural Networks**: $$ (f * g)[n] = \sum_m f[m] \cdot g[n-m] $$ - Feature extraction through learned filters - Pooling for translation invariance **Anomaly Detection**: - Autoencoders: $\text{loss} = \|x - D(E(x))\|^2$ - Isolation Forest: anomaly score based on path length ### 10.3 Process Optimization **Bayesian Optimization**: $$ x_{next} = \arg\max_x \alpha(x | \mathcal{D}) $$ **Acquisition Functions**: - Expected Improvement: $\alpha_{EI}(x) = \mathbb{E}[\max(f(x) - f^*, 0)]$ - Upper Confidence Bound: $\alpha_{UCB}(x) = \mu(x) + \kappa \sigma(x)$ ## Summary Table | Domain | Key Mathematical Topics | |--------|-------------------------| | **Lithography** | Fourier analysis, inverse problems, PDEs, optimization | | **Device Physics** | Quantum mechanics, functional analysis, group theory | | **Process Simulation** | Nonlinear PDEs, Monte Carlo, stochastic processes | | **Electromagnetics** | Maxwell's equations, BEM, PEEC, capacitance/inductance extraction | | **Statistics** | Multivariate Gaussian, PCA, polynomial chaos, yield models | | **Optimization** | Response surface, inverse problems, Levenberg-Marquardt | | **Physical Design** | Graph theory, combinatorial optimization, ILP, Steiner trees | | **Thermal/Mechanical** | Continuum mechanics, FEM, tensor analysis | | **Atomistic Modeling** | Statistical mechanics, DFT, KMC, molecular dynamics | | **Machine Learning** | Neural networks, Bayesian inference, optimization |

advantage actor-critic, a2c, reinforcement learning

Synchronous actor-critic.

adversarial augmentation, data augmentation

Generate adversarial examples for training.

adversarial debiasing, evaluation

Adversarial debiasing uses adversarial training to remove protected attribute information.

adversarial debiasing,debiasing

Train adversary that can't predict protected attributes.

adversarial example, interpretability

Adversarial examples are imperceptibly perturbed inputs causing misclassification revealing model vulnerabilities.

adversarial example,perturbation,attack

Adversarial examples are inputs crafted to fool models. Small perturbations cause wrong predictions.

adversarial examples for interpretability, explainable ai

Use adversarial examples to probe model understanding.

adversarial examples,ai safety

Inputs designed to fool the model into wrong predictions.

adversarial loss in generation, generative models

GAN-style discriminator loss.

adversarial nli, evaluation

Hard NLI examples.

adversarial perturbation budget, ai safety

Maximum allowed perturbation size.

adversarial prompt, ai safety

Adversarial prompts attempt to elicit undesired behaviors testing model robustness.

adversarial prompting, ai safety

Test model robustness with adversarial inputs.

adversarial robustness evaluation, ai safety

Measure resilience to adversarial attacks.

adversarial robustness, interpretability

Adversarial robustness measures model resilience to adversarial perturbations.

adversarial suffix attack,ai safety

Append carefully crafted text to jailbreak model.

adversarial training defense, interpretability

Adversarial training improves robustness by augmenting training with adversarial examples.

adversarial training for safety,ai safety

Train on adversarial examples to improve robustness.

adversarial training, at, ai safety

Train on adversarial examples.

adversarial training,ai safety

Train on adversarial examples to make model more robust.

adversarial training,robust,defense

Adversarial training includes adversarial examples in training. Makes models more robust. Expensive.

adversarial watermark removal,security

Attacks to remove watermarks.

adversarial weight perturbation, awp, ai safety

Perturb weights for robustness.

adverse event detection, healthcare ai

Find medication side effects in text.

aerial image inspection, lithography

Inspect simulated image from mask.

affective computing,emerging tech

AI that recognizes and responds to emotions.

affinity diagram, quality & reliability

Affinity diagrams group related ideas revealing patterns and themes.

afm (atomic force microscopy),afm,atomic force microscopy,metrology

Scan surface with sharp tip to measure topography at nanometer scale.

afm, afm, recommendation systems

Attentional Factorization Machines use attention weights to learn importance of different feature interactions.

aft, aft, llm architecture

Attention Free Transformer uses element-wise operations instead of attention.

agent approval, ai agents

Agent approval requires human confirmation before executing high-stakes actions.

agent benchmarking, ai agents

Agent benchmarking evaluates performance across standardized task suites.

agent communication, ai agents

Agent communication protocols enable information exchange and coordination between agents.

agent debugging, ai agents

Agent debugging identifies and resolves issues in planning and execution logic.

agent feedback loop, ai agents

Feedback loops allow humans to correct and guide agent behavior iteratively.

agent handoff, ai agents

Agent handoff transfers responsibility for tasks between agents smoothly.

agent logging, ai agents

Agent logging records decisions actions and reasoning for debugging and auditing.

agent loop, ai agents

Agent loops repeatedly observe plan act and update until objectives are achieved.

agent memory, ai agents

Agent memory maintains conversation history observations and learned information across interactions.

agent negotiation, ai agents

Agent negotiation resolves conflicts through offers counteroffers and compromise.