Analog-to-digital converter

• US 5,481,129 A
• Filed: 02/21/1995
• Issued: 01/02/1996
• Est. Priority Date: 10/30/1991
• Status: Expired due to Term

• Current Assignee: Intersil Corporation (Renesas Electronics Corporation)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Johnston, Jeffrey M., Kutchmarick, Dave, DeJong, Glenn A., Church, Michael D., Ito, Akira, Gasner, John T., Fisher, Gregory J., Bacrania, Kantilal, Rhee, Choong-Sun
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): WILLIAMS, ALEXANDER O
• Application Number:
  US08/391,490
• Time in Patent Office: 315 Days
• Field of Search: 257/536, 257/537, 257/370, 257/357, 257/371, 257/360, 257/361, 257/363, 257/154, 257/379, 257/358, 257/486, 437/63
• US Class Current: 257/360
• CPC Class Codes: G05F 3/30 Regulators using the difference between the base-emitter voltages of two bipolar transistors operating at different current densities G05F3/26 takes precedence
• CPC Class Codes: G11C 27/026 associated with an amplifier G11C27/028 takes precedence
• CPC Class Codes: H01L 21/8249 Bipolar and MOS technology
• CPC Class Codes: H01L 27/0214 for internal polarisation, e.g. I2L
• CPC Class Codes: H01L 27/0623 in combination with bipolar transistors
• CPC Class Codes: H01L 27/0635 in combination with bipolar transistors and diodes, or resistors, or capacitors
• CPC Class Codes: H03F 1/523 for amplifiers using field-effect devices H03F1/526 takes precedence
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 3/505 with field-effect devices
• CPC Class Codes: H03G 1/0082 using bipolar transistor-type devices
• CPC Class Codes: H03K 17/223 in field-effect transistor switches
• CPC Class Codes: H03K 5/15 Arrangements in which pulses are delivered at different times at several outputs, i.e. pulse distributors distributing, switching or gating arrangements H03K17/00
• CPC Class Codes: H03M 1/162 the steps being performed sequentially in a single stage, i.e. recirculation type H03M1/161 takes precedence
• CPC Class Codes: H03M 1/365 the voltage divider being a single resistor string

Abstract

A two-step analog-to-digital converter and BiCMOS fabrication method. The fabrication method provides pseudosubstrate isolation of digital CMOS devices from the analog devices. The converter uses NPN current switching in a flash analog-to-digital converter and in a digital-to-analog converter for low noise operation. CMOS digital error correction and BiCMOS output drivers provide high packing density plus large output load handling. Timing control aggregates switching events and puts them into intervals when noise sensitive operations are inactive. The fabrication method uses a thin epitaxial layer with limited thermal processing to provide NPN and PNP devices with large breakdown and Early voltages. Laser trimmed resistors provide small long term drift due to dopant stabilization in underlying BPSG and low hydrogen nitride passivation.

Claims

1. An integrated circuit, comprising:

(a) a laser-trimmed resistor; and

(b) a silicon nitride layer over said resistor, said layer characterized by a silicon-hydrogen bonded content of an amount in a range between 0 and approximately 12% atomic.

2. An integrated circuit, comprising:

(a) a layer of borophosphosilicate glass (BPSG) over a substrate, said BPSG layer comprising enough oxidized boron and enough oxidized phosphorous to lessen the out diffusion of both said boron and phosphorous; and

(b) a precision thin film metal resistor on said BPSG layer.

4. The integrated circuit of claim 2 wherein the metal comprises a metal alloy.

5. The integrated circuit of claim 2 wherein the metal resistor comprises NiCr.

6. The integrated circuit of claim 2 wherein most of the boron and most of the phosphorus are oxidized.

7. The integrated circuit of claim 2 wherein the amount of boron in the precision thin film metal resistor is greater than zero and less than 1×

10²⁰ /cm³.

8. The integrated circuit of claim 2 wherein the amount of boron in the precision thin film metal resistor is greater than zero and less than 4×

10¹⁹ /cm³.

9. The integrated circuit of claim 2 wherein the precision thin metal resistor is about 100 Angstroms thick.

3. An integrated circuit, comprising:

(a) a layer of borophosphosilicate glass (BPSG) overlying a substrate; and

(b) a precision thin film metal resistor on said BPSG layer, said resistor with a boron concentration in a range greater than 0 and less than 4×

10¹⁹ atoms/cm³.

10. The integrated circuit of claim 3 wherein the metal comprises a metal alloy.

11. The integrated circuit of claim 3 wherein the metal resistor comprises NiCr.

12. The integrated circuit of claim 3 wherein most of the boron and most of the phosphorus are oxidized.

13. The integrated circuit of claim 3 wherein the precision thin metal resistor is about 100 Angstroms thick.

14. An integrated circuit, comprising:

(a) a layer of borophosphosilicate glass (BPSG) over a substrate, said BPSG layer having most of the boron oxidized and most of the phosphorous to retain the boron and phosphorous in the BPSG layer; and

(b) a precision thin film metal resistor on said BPSG layer.