I recently read an article that stated 70% of the world's semiconductors are through Taiwan.

That's one reason China wants to take them. Another is that conquering Taiwan gives China strategic position of the First Island Chain. They will then be positioned to expand into the Pacific, a threat to Guam and possibly even Hawaii later on.

China also feels it has a bone to pick with Taiwan because a lot of Chiang Kai-shek's forces retreated there after their Civil War. However, Taiwan has never been part of China. In fact, their native people have a culture and language more akin to islands in the Pacific.