Method for Programming Cells of an Array of Row and Column Lines with Cells in Intersection Areas of the Lines with Programmable Contents

Simple SummaryContent extracted from patent full text and abstract with AI.

This invention describes a method for programming cells in a crossbar memory array — a grid where row and column lines intersect at programmable memory cells. When a group of cells needs to be programmed to essentially the same content (values differing by no more than a defined threshold), the method first programs one "reference" cell by iteratively applying variable programming voltages and reading back the cell's content until the desired value is reached. The exact sequence of programming voltages that successfully programmed that first cell is then replayed, in the same order, on every remaining cell in the group — eliminating the need to repeat the full iterative search for each cell individually.

Use CasesContent extracted from patent full text and abstract with AI.

• Programming large blocks of resistive RAM (ReRAM/RRAM) cells to the same resistance level in neuromorphic computing hardware, where many synaptic weights share the same value.
• Initializing phase-change memory (PCM) arrays used in storage-class memory devices where entire pages or rows must be set to a uniform state.
• Calibrating analog in-memory computing arrays (e.g., for matrix-vector multiplication accelerators) where multiple cells must hold identical analog conductance values.
• Manufacturing test and burn-in of crosspoint memory arrays, where uniform cell states are required to verify array uniformity and yield.
• Programming lookup tables or weight matrices in embedded non-volatile memory for edge-AI inference chips where repeated weight values are common.

BenefitsContent extracted from patent full text and abstract with AI.

• Significantly reduces total programming time for groups of identically-valued cells by avoiding the full iterative write-verify loop for every cell after the first.
• Lowers the number of read operations required during programming, reducing stress and wear on memory cells in the array.
• Improves programming consistency across a group of cells by applying the exact same voltage sequence, leading to tighter distribution of programmed values.
• Simplifies the control logic needed for group programming, since the voltage sequence is recorded once and then replayed without further decision-making.
• Reduces energy consumption during bulk programming operations by eliminating redundant iterative verification cycles for cells after the reference cell.

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Patent Abstract

With the method described here, cells of an array are programmed using row lines (16) and column lines (18) with cells (12) at intersection areas of the lines (16, 18), wherein the contents to be programmed of the cells (12) of a group (20) of cells (12) comprising at least two cells (12) are substantially equal, i.e., deviate from one another by at most a predefinable threshold value. The programming of a first cell (12) of the group (20) is carried out by means of the step of applying a variable programming voltage and the subsequent step of reading out the contents, wherein these two steps are performed multiple times until the cell (12) is programmed with the desired contents. Each further cell (12) of this group (20) is programmed by means of successive execution of the steps of applying the programming voltages that were previously applied to the first cell (12).