A Silicon Valley chip startup backed by Microsoft Corp. and Dell Technologies Inc. accused a top executive at Huawei Technologies Co., Deputy Chairman Eric Xu, of participating in a conspiracy to steal its trade secrets, court documents show.

The allegations were made in a lawsuit set for trial June 3 in federal court in the Eastern District of Texas, in which CNEX Labs Inc. claims Huawei engaged in a multiyear conspiracy to steal the San Jose, Calif., company’s solid-state drive computer storage technology, including with...