It wasn't that, not at the start. Soviets were cloning US semiconductors right from the very first days of the industries existence when they were mostly selling chips to the US military. There wasn't a huge consumer base back then keeping them afloat, and the Soviet chip industry was highly prioritized by the Kremlin. They even built an entire city called Zelenograd just to house the semiconductor workforce.

The Soviets did try to design their own chips in the beginning. But it was a lost cause because they simply couldn't keep up with the advances of the West.