Chinese regulators have been investigating memory-chip makers Micron Technology Inc. (MU  ), Samsung Electronics Co. (KRX: 005930), and SK Hynix Inc. (KRX: 000660). All three companies reported thatChina's State Administration for Market Regulation paid visits to their offices in China.

A spokesman for SK Hynix said the investigation is over suspected price fixing. Samsung and Micron did not comment on the subject of the investigation.

China purchases an estimated 90% of its semiconductors from foreign companies to be used in everything from smartphones to automobiles. Demand in the country, which already purchases more than 60% of the world's chips, is expected to increase from $350 billion in 2016 to $500 billion by 2020, according to McKinsey.

The country has been locked in a dispute with the United States over technology for months. The biggest flashpoint is Chinese smartphone maker ZTE (HKG: 0763), which has been banned from buying parts, including chips, from American companies. The ban brought ZTE factories to a standstill and the company still faces an uncertain future.

However, the American government announced a deal Thursday to lift a ban on ZTE from buying parts, including chips, from American companies. This comes at a time when President Xi Jinping is attempting to shore up the domestic chip industry. Right now, China relies heavily on foreign companies for the core technology that powers everything from smartphones to automobiles. Foreign companies filled 90% of China's insatiable appetite for chips last year, according to technology consultancy International Business Strategies.

Thus, it is questionable whether the government is shooting itself in the foot by trying to augment domestic chip production when so much of the industry relies on imported products.

Xi has made clear the importance he attaches to the semiconductor industry, recently comparing a computer chip to the human heart.

"No matter how big a person is, he or she can never be strong without a sound and strong heart," he said in April, during a visit to a semiconductor factory in central China.

"The US feels China is using 'unfair' means to obtain technological know-how from the US and elsewhere and is 'unfairly' using subsidies and other industrial policies," Louis Kuijs, head of Asian economics at research firm Oxford Economics, wrote in a research note last week.

Analysts have suggested the investigation into South Korean and US memory chip makers could be a way of putting pressure on the companies to share intellectual property and boost Chinese competitors.

The White House has said it will impose tariffs on about $50 billion worth of Chinese goods following an investigation into the country's handling of technology transfers and intellectual property.