What is temporary storage on chips called?

Temporary storage on chips is called memory.

Most such solid-state memory is in the form of random-access memory (RAM) chips, usually dynamic RAM (DRAM).

The people who write operating systems and the computer architects that design computer systems and CPUs often use many different temporary storage areas, each one with a different name.

If you are building a high-speed computer or writing a high-performance operating system, you will learn about the temporary storage areas known as the disk page cache, the stack, the heap, and the virtual memory page table, are (more or less) stored in the main memory DRAM.

The CPU has a few temporary locations called registers.

Often there is one or more levels of cache (the L1 cache, the L2 cache, etc.) between the CPU and the main memory. High-performance CPUs typically put a cache on the same chip as the CPU; some older personal computers had an "external cache" SRAM chips between the CPU chip and the main memory DRAM chips.

Many high-performance computers have several levels of successively larger and slower caches -- an extremely fast I-cache and D-cache and TLB, the L1 cache, the L2 cache, the L3 cache, and main memory.