With　a　two-stage　method,　cubic　boron　nitride　(c-BN)　thin　films　are　deposited　on　p-Si　(100)　by　radio　frequency　sputter.　The　thin　films　are　characterized　by　Fourier　transform　infrared　spectroscopy.　With　all　other　conditions　being　held　constant,　the　influence　of　the　substrate　temperature　on　the　nucleation　of　c-BN　is　investigated.　When　the　substrate　temperature　is　below　400°C,　the　cubic　phase　can　not　be　formed.　Once　the　substrate　temperature　is　above　400°C,　the　cubic　phase　starts　to　form.　When　the　substrate　temperature　reaches　500°C,　there　is　only　the　cubic　phase　(100%)　in　the　thin　films.　It　is　evident　that　the　relative　content　of　c-BN　in　the　films　increases　with　the　increase　of　the　substrate　temperature　in　the　nucleation　stage.　We　also　investigate　the　effect　of　the　substrate　temperature　in　the　nucleation　stage　on　the　FTIR　absorption　peak　position　and　compressive　stress　in　the　thin　films.　The　results　show　that　different　substrate　temperatures　in　the　nucleation　stage　result　in　different　compressive　stress　in　the　thin　films　and　that　the　compressive　stress　in　the　thin　films　decreases　with　the　increase　of　the　substrate　temperature　in　the　nucleation　stage.　The　mechanism　of　c-BN　nucleation　is　also　discussed.