In a semiconductor device having an SOI structure and a method of manufacturing the same, influence by a parasitic transistor can be prevented, and no disadvantage is caused in connection with a manufacturing process. In this semiconductor device, an upper side portion of a semiconductor layer is rounded. Thereby, concentration of an electric field at the upper side portion of the semiconductor layer can be prevented. As a result, lowering of a threshold voltage of a parasitic transistor can be prevented, so that the parasitic transistor does not adversely affect subthreshold characteristics of a regular transistor. Owing to provision of a concavity of a U-shaped section, generation of etching residue can be prevented when etching a gate electrode for patterning the same. Thereby, a disadvantage is not caused in connection with the manufacturing process.
This application is a divisional of application Ser. No. 08/794,504 filed Feb. 4, 1997 now U.S. Pat. No. 5,905,286 which is a continuation of application Ser. No. 08/461,777, filed Jun. 5, 1995 now abandoned.
Priority Data
Nov 02, 1994 [JP] 6-269695 Dec 15, 1994 [JP] 6-334025
The invention provides a semiconductor device having the trench-shaped isolator is provided with a portion which is adjacent to the semiconductor element region, of which the width is continuously decreased in the downward direction, and of which the surface is planarized near the semiconductor element region, for relaxing the stress in the silicon layer and being flat the surface of the trench-shaped insulator, and method of manufacturing the same.
A semiconductor device having a trench-shaped isolator, adjacent to the semiconductor element region is formed having a width which is continuously decreased in the downward direction for relaxing the stress in the silicon layer. Embodiments include forming a patterned dielectric layer on an SOI substrate, forming sidewall spacers thereon, and etching the underlying silicon layer followed by oxidation or controlled etching to form the trench with downwardly decreasing side surfaces.
Semiconductor devices have device regions in which semiconductor properties such as spreading resistivity and its profile are significant. In making a p-type device region on a semiconductor wafer, an initial semiconductor device region is defined by a buried region, and an initial spreading resistivity profile is developed by annealing. After annealing, semiconductor device properties can be enhanced by removing a surface sub-region of the initial device region, and can be further improved by epitaxially growing thereon a monocrystalline film as an improved channel layer for FET devices. Such properties are relevant in MOS as well as bipolar devices.
A silicon-on-insulator (SOI) device structure 100 formed using a self-aligned body tie (SABT) process. The SABT process connects the silicon body of a partially depleted (PD) structure to a bias terminal. In addition, the SABT process creates a self-aligned area of silicon around the edge of the active areas, as defined by the standard transistor active area mask, providing an area efficient device layout. By reducing the overall gate area, the speed and yield of the device may be increased. In addition, the process flow minimizes the sensitivity of critical device parameters due to misalignment and critical dimension control. The SABT process also suppresses the parasitic gate capacitance created with standard body tie techniques.
A silicon-on-insulator (SOI) device structure 100 formed using a self-aligned body tie (SABT) process. The SABT process connects the silicon body of a partially depleted (PD) structure to a bias terminal. In addition, the SABT process creates a self-aligned area of silicon around the edge of the active areas, as defined by the standard transistor active area mask, providing an area efficient device layout. By reducing the overall gate area, the speed and yield of the device may be increased. In addition, the process flow minimizes the sensitivity of critical device parameters due to misalignment and critical dimension control. The SABT process also suppresses the parasitic gate capacitance created with standard body tie techniques.
