In an electrical characteristic inspection of a semiconductor integrated circuit, such as one in an integrated circuit (IC) chip, a conductive contact unit is used to hold a plurality of conductive contacts at predetermined positions that correspond to a pattern of electrodes for external connections on the semiconductor integrated circuit. Such a conductive contact unit includes a conductive contact holder including a substrate made of a conductive material and holes for inserting the conductive contacts.
To implement high-speed processing, a recent semiconductor integrated circuit operates with a high frequency electrical signal (a high frequency signal) at a frequency of about several hundred mega hertz (MHz) to several hundred gigahertz (GHz). To form a conductive contact unit that can support such a high frequency signal, it is preferable to make the external diameter of the conductive contact as small as possible. As a technology for supporting a high frequency signal, a conductive contact holder is known that includes a metal holder substrate having openings in which insulating members, each having a hollow, are embedded. The conductive contacts are inserted in the hollows to be held therein (for example, see Patent Documents 1 to 3).
Such a conductive contact holder is manufactured by inserting the insulating member having a hollow created in advance through hole machining into the holder substrate, or after embedding the insulating member into the opening of the holder substrate, a hollow is formed in the insulating member through hole machining.    [Patent Document 1] Japanese Patent Application Laid-open No. 2004-259648    [Patent Document 2] Japanese Patent No. 3500105    [Patent Document 3] International Publication No. 03/087852