Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
255 words
A thin film transistor of silicon-on-insulator type comprising: a buried oxide layer (20, 20A, 20B) formed on a semiconductor substrate (10, 10A, 10B); a silicon layer (30, 30A, 30B) of a first conductive type formed on said buried oxide layer, said silicon layer having a body region (31, 31A, 31B) of a second conductive type, source region (33, 33A, 33B) of said first conductive type, drain region (32, 32A, 32B) of said first conductive type, and a drift region (34, 34A, 34B) of said first conductive type formed between said source and drain regions, said source region being formed in said body region to be spaced from said buried oxide layer; an upper oxide layer (40, 40A, 40B) formed on said silicon layer; a source electrode (60, 60A, 60B) contacting both of said body region and said source region; a drain electrode (50, 50A, 50B) contacting said drain region; and a gate electrode (70, 70A, 70B) disposed between said source and drain electrodes and spaced from said silicon layer by a thin oxide layer (41, 41A, 41B); wherein said silicon layer is formed with a first portion (38, 38A, 38B) of a thickness (T1) in which said drift region is formed, and a second portion (36, 36A, 36B) of a thickness (T2) in which said body region is formed to reach said buried oxide layer, and wherein said thicknesses (T1) and (T2) are determined so as to satisfy the following relationships: 0.4 µm < T1 0.4 µm ≤ T2 ≤ 1.5 µm T2 < T1.
Claim 2
Dependent Claim
22 words
A thin film transistor as set forth in claim 1, wherein said first and second conductive types are n-type and p-type, respectively.
Claim 3
Dependent Claim
26 words
A thin film transistor as set forth in claim 1, wherein said drift region (34A, 34B) is formed with a lateral linear doping region (35A, 35B).
Claim 4
Dependent Claim
58 words
A thin film transistor as set froth in claim 3, wherein said gate electrode (70A, 70B) has a field plate (71A, 71B) which is short-circuited to said gate electrode, and wherein said gate electrode and field plate extend laterally in a spaced relation from said silicon layer (30A, 30B) and without overlying said linear doping region (35A, 35B).
Claim 5
Dependent Claim
19 words
A thin film transistor as set forth in claim 1, wherein said thickness (T1) is 1 µm or more.
Claim 6
Dependent Claim
90 words
A thin film transistor as set froth in claim 1, wherein said silicon layer (30A, 30B) is formed on its upper surface with a slope (37A, 37B) extending from said second portion (36A, 36B) to said first portion (38A, 38B), said body region (31A, 31B) extending along said slope from said second portion toward said first portion, said gate electrode (70A, 70B) having a field plate (71A, 71B) which extends in parallel with said slope and in a spaced relation from said slope by said thin oxide layer (41A, 41B).
Claim 7
Dependent Claim
37 words
A thin film transistor as set forth in claim 1, wherein said drain region (32, 32A, 32B) is formed in said silicon layer (30, 30A, 30B) to be spaced from said buried oxide layer (20, 20A, 20B).