WASHINGTON (Reuters) -Ukraine's two leading suppliers of neon, which produce about half the world's supply of the key ingredient for making chips, have halted their operations as Moscow has sharpened its attack on the country, threatening to raise prices and aggravate the semiconductor shortage. Some 45% to 54% of the world's semiconductor-grade neon, critical for the lasers used to make chips, comes from two Ukrainian companies, Ingas and Cryoin, according to Reuters calculations based on figures from the companies and market research firm Techcet. Global neon consumption for chip production reached about 540 metric tons last year, Techcet estimates. Both...