Deepak A Ramappa

7745238, Jun 29, 2010

Feb 26, 2008

12/037531

Deepak A. Ramappa - Cambridge MA, US
Laura Matz - Macungie PA, US

Texas Instruments Incorporated - Dallas TX

G01R 31/26
H01L 21/66

438 14, 257E21521, 257E21529

A method of measuring temperature across wafers during semiconductor processing includes the step of providing a correlation between a peak wafer temperature during a processing step and a change in wafer surface charge or surface potential following the processing step. A first wafer to be characterized for its peak temperature spatial distribution during the processing step is processed through the processing step. The wafer surface charge or surface potential at a plurality of locations on the first wafer are measured following the processing step. A peak temperature spatial distribution for the first wafer is then determined based on the correlation and the wafer surface charge or surface potential measured in the measuring step.

7767583, Aug 3, 2010

Dec 10, 2008

12/331937

Deepak Ramappa - Cambridge MA, US
Thirumal Thanigaivelan - North Andover MA, US

Varian Semiconductor Equipment Associates, Inc. - Gloucester MA

H01L 21/302

438705, 438407, 438423, 438440, 438480, 438514, 438515, 438516, 438517, 438518, 438519, 438520, 438528, 438659, 438766

Embodiments of this method improve the results of a chemical mechanical polishing (CMP) process. A surface is implanted with a species, such as, for example, Si, Ge, As, B, P, H, He, Ne, Ar, Kr, Xe, and C. The implant of this species will at least affect dishing, erosion, and polishing rates of the CMP process. The species may be selected in one embodiment to either accelerate or decelerate the CMP process. The dose of the species may be varied over the surface in one particular embodiment.

7868306, Jan 11, 2011

Oct 2, 2008

12/243992

Deepak A. Ramappa - Cambridge MA, US

Varian Semiconductor Equipment Associates, Inc. - Gloucester MA

H01J 37/317
H01L 21/265

25049221, 2504922, 2504923, 2504431, 438530

A method for ion implantation is disclosed which includes modulating the temperature of the substrate during the implant process. This modulation affects the properties of the substrate, and can be used to minimize EOR defects, selectively segregate and diffuse out secondary dopants, maximize or minimize the amorphous region, and vary other semiconductor parameters. In one particular embodiment, a combination of temperature modulated ion implants are used. Ion implantation at higher temperatures is used in sequence with regular baseline processing and with ion implantation at cold temperatures. The temperature modulation could be at the beginning or at the end of the process to alleviate the detrimental secondary dopant effects.

7902091, Mar 8, 2011

Aug 11, 2009

12/538903

Deepak A. Ramappa - Cambridge MA, US

Varian Semiconductor Equipment Associates, Inc. - Gloucester MA

H01L 21/00

438795, 438455, 438458, 257E21001, 257E21328

An improved process of substrate cleaving and a device to perform the cleaving are disclosed. In the traditional cleaving process, a layer of microbubbles is created within a substrate through the implantation of ions of a gaseous species, such as hydrogen or helium. The size and spatial distribution of these microbubbles is enhanced through the use of ultrasound energy. The ultrasound energy causes smaller microbubbles to join together and also reduces the straggle. An ultrasonic transducer is acoustically linked with the substrate to facilitate these effects. In some embodiments, the ultrasonic transducer is in communication with the platen, such that ultrasound energy can be applied during ion implantation and/or immediately thereafter. In other embodiments, the ultrasonic energy is applied to the substrate during a subsequent process, such as an anneal.

8148237, Apr 3, 2012

Aug 5, 2010

12/851168

Deepak Ramappa - Cambridge MA, US
Julian G. Blake - Gloucester MA, US

Varian Semiconductor Equipment Associates, Inc. - Gloucester MA

H01L 21/46

438456, 438977, 257E21211

A method of cleaving a substrate is disclosed. A species, such as hydrogen or helium, is implanted into a substrate to form a layer of microbubbles. The substrate is then annealed a pressure greater than atmosphere. This annealing may be performed in the presence of the species that was implanted. This diffuses the species into the substrate. The substrate is then cleaved along the layer of microbubbles. Other steps to form an oxide layer or to bond to a handle also may be included.

8153496, Apr 10, 2012

Mar 7, 2011

13/041724

Deepak Ramappa - Cambridge MA, US

Varian Semiconductor Equipment Associates, Inc. - Gloucester MA

H01L 21/331

438369, 438364, 438514, 257E21043

An improved method of doping a substrate is disclosed. The method is particularly beneficial to the creation of interdigitated back contact (IBC) solar cells. A patterned implant is performed to introduce a first dopant to a portion of the solar cell. After this implant is done, an oxidation layer is grown on the surface. The oxide layer grows more quickly over the implanted region than over the non-implanted region. An etching process is then performed to remove a thickness of oxide, which is equal to the thickness over the non-implanted regions. A second blanket implant is then performed. Due to the presence of oxide on portions of the solar cell, this blanket implant only implants ions in those regions which were not implanted previously.

8183546, May 22, 2012

Feb 25, 2010

12/712816

Deepak A. Ramappa - Cambridge MA, US

VARIAN Semiconductor Equipment Associates, Inc. - Gloucester MA

G21K 5/04

2504923, 250251, 2504921, 2504922, 25049222

Ions are generated and directed toward a workpiece. A laser source generates a laser that is projected above the workpiece in a line. As the laser is generated, a fraction of the ions are blocked by the laser. This may enable selective implantation or modification of the workpiece. In one particular embodiment, the lasers are generated while ions are directed toward the workpiece and then stopped. Ions are still directed toward the workpiece after the lasers are stopped.

8187979, May 29, 2012

Dec 23, 2009

12/646407

Deepak A. Ramappa - Cambridge MA, US
Ludovic Godet - North Reading MA, US

Varian Semiconductor Equipment Associates, Inc. - Gloucester MA

H01L 31/18

438710, 438 71, 136250, 136256

Methods to texture or fabricate workpieces are disclosed. The workpiece may be, for example, a solar cell. This texturing may involve etching or localized sputtering using a plasma where a shape of a boundary between the plasma and the plasma sheath is modified with an insulating modifier. The workpiece may be rotated in between etching or sputtering steps to form pyramids. Regions of the workpiece also may be etched or sputtered with ions formed from a plasma adjusted by an insulating modifier and doped. A metal layer may be formed on these doped regions.