Methods to improve the operation of SOI devices

• US 7,405,982 B1
• Filed: 06/07/2000
• Issued: 07/29/2008
• Est. Priority Date: 04/23/1997
• Status: Expired due to Fees

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Hsu, Louis L., Kuang, Jente B.
• Primary Examiner(s): Jackson; Jerome
• Assistant Examiner(s): Budd; Paul A.
• Application Number:
  US09/588,351
• Time in Patent Office: 2,974 Days
• Field of Search: 257/347-354
• US Class Current: 365/189.09
• CPC Class Codes: G11C 16/08 Address circuits; Decoders; Word-line control circuits
• CPC Class Codes: H01L 27/1203 the substrate comprising an insulating body on a semiconductor body, e.g. SOI three-dimensional layout H01L27/0688

Abstract

According to the present invention, a circuit and methods for enhancing the operation of SOI fabricated devices are disclosed. In a preferred embodiment of the present invention, a pulse discharge circuit is provided. Here, a circuit is designed to provide a pulse that will discharge the accumulated electrical charge on the body of the SOI devices in the memory subarray just prior to the first access cycle. As explained above, once the accumulated charge has been dissipated, the speed penalty for successive accesses to the memory subarray is eliminated or greatly reduced. With a proper control signal, timing and sizing, this can be a very effective method to solve the problem associated with the SOI loading effect. Alternatively, instead of connecting the bodies of all SOI devices in a memory circuit to ground, the bodies of the N-channel FET pull-down devices of the local word line drivers can be selectively connected to a reference ground. This would enable the circuit to retain most of the speed advantages associated with SOI devices while overcoming the loading problem described above. With this preferred embodiment of the present invention, the major delay caused by the bipolar loading effect is minimized while the speed advantage due to providing a lower, variable Vt effect is preserved. The overall body resistance of the individual devices has a minimal effect on the device body potential.

Claims

1. A method for discharging accumulated charge from a body of an SOI device and accessing the SOI device, comprising:

generating a pulse;

using the generated pulse to provide a conductive path from the body of the SOI device to a reference point having a lower potential than the accumulated charge;

discharging the accumulated charge from the body of the SOI device to the reference point;

providing a control signal which enables access to the SOI device; and

reading an output of the SOI device,

wherein said steps of generating a pulse and discharging the accumulated charge occur prior to said step of reading an output of the SOI device.

2. In a circuit comprising a plurality of SOI devices, wherein said plurality of SOI devices comprises a memory circuit and wherein each of the plurality of SOI devices has a body, a method for enhancing the performance of the circuit, the method comprising:

providing a pulse discharge circuit, the pulse discharge circuit having a pulse generator connected to the circuit;

using the pulse generator to generate a pulse; and

discharging any accumulated potential on the body of at least one of the plurality of SOI devices to a point having a lower potential than the accumulated potential of the body in response to the pulse from the pulse generator just prior to accessing the memory circuit for reading or writing data.