A high purity fluid control valve includes a moveable control plate having a flow-through passage to enhance fluid sweep of the internal valve volume. The valve is of jet and seat type using nested orifice ridges to achieve high conductance with small actuator movement. Enhanced leak tightness in the valve shut-off condition may additionally be provided by selectively incorporating into the control plate materials softer than the material comprising the orifice ridge. The control plate is especially useful in high conductance, fast acting, and proportional control applications such as gas delivery in semiconductor manufacturing.