Method for manufacturing high-frequency signal transmission circuit and high-frequency signal transmission circuit device

Abstract

A method for manufacturing a high-frequency signal transmission circuit includes the steps of forming a groove to surround a first region on a semiconductor substrate, filling the groove with a stopper material, forming a high-frequency transmission line on the semiconductor substrate so that the transmission line extends over the first region, and etching the first region of the semiconductor substrate using the stopper material as an etching stopper to form a recess in the first region.

1 . A method for manufacturing a high-frequency signal transmission circuit comprising the steps of:
 forming a groove to surround a first region on a semiconductor substrate;   filling the groove with a stopper material;   forming a high-frequency signal transmission line on the semiconductor substrate so that the transmission line extends over the first region; and   etching the first region of the semiconductor substrate using the stopper material as an etching stopper to form a recess in the first region.   
   
   
       2 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 1 , wherein the stopper material is an insulator. 
   
   
       3 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 2 , wherein the step of forming the recess includes the steps of:
 forming slits in an insulating film along the boundary between the first region and a second region of the semiconductor substrate, which is other than the first region; and   etching the first region after the slits are formed in the insulating film.   
   
   
       4 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 2 , further comprising the step of forming an insulating film on the semiconductor substrate in which the groove has been formed, wherein the step of forming the insulating film includes the step of filling the groove with a material of the insulating film as the stopper material. 
   
   
       5 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 4 , wherein the step of forming the recess includes the steps of:
 forming slits in the insulating film along the boundary between the first region and a second region of the substrate, which is other than the first region; and   etching the first region after the slits are formed in the insulating film.   
   
   
       6 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 1 , wherein the stopper material is a conductor. 
   
   
       7 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 6 , further comprising the step of forming an insulating film on the semiconductor substrate between the step of filling the groove with the conductor used as the stopper material and the step of forming the transmission line. 
   
   
       8 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 7 , wherein the step of forming the recess includes the steps of:
 forming slits in at least the insulating film along the boundary between the first region and a second region of the semiconductor substrate, which is other than the first region, after the insulating film is formed; and   etching the first region after the slits are formed in the insulating film.   
   
   
       9 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 6 , further comprising the step of forming a conductor film on the semiconductor substrate in which the groove has been formed,
 wherein the step of forming the conductor film includes the step of filling the groove with a material of the conductor film.   
   
   
       10 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 6 , further comprising the step of forming a conductor to coat a surface of the recess formed by the etching. 
   
   
       11 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 1 , wherein the step of forming the groove includes the steps of:
 forming a first groove to surround the first region; and   forming a second groove near the portion where the first groove is formed;   the step of filling the grooves with the stopper material includes the step of filling the first groove with the stopper material composed of a first material, and the step of filling the second groove with a second material different from the first material.   
   
   
       12 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 1 , wherein the step of filling the groove with the stopper material includes the steps of:
 forming a first film composed of a first material at least in the groove; and   forming a second film composed of a second material on the first film at least in the groove, the second material being different from the first material.   
   
   
       13 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 1 , wherein the step of forming the transmission line includes the steps of:
 forming a first portion having a first width of the transmission line on the first region; and   forming a second portion having a second width on a second region other than the first region of the semiconductor substrate, the second width being different from the first width of the transmission line.   
   
   
       14 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 1 , wherein the step of forming the recess includes the step of controlling the depth of the recess. 
   
   
       15 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 1 , wherein the step of forming the recess includes the step of determining the depth of the recess on the basis of the capacitance of the transmission line. 
   
   
       16 . The method for manufacturing a high-frequency signal transmission circuit according to  claim 14 , wherein the step of controlling the depth of the recess includes the steps of:
 measuring the characteristic impedance of the transmission line; and   controlling the depth according to the measurement result.