Planarization control in semiconductor manufacturing process

A method of forming a semiconductor device, comprising:

• forming a patterned layer on a substrate;
• depositing a polysilicon layer on the patterned layer;
• depositing a sacrificial layer on the polysilicon layer, the sacrificial layer having a material different from polysilicon;
• chemical mechanical polishing a first portion of the sacrificial layer using a slurry having a first selectivity of material to polysilicon greater than about 1:20, wherein the chemical mechanical polishing is performed at a temperature from about 20° C. to about 60° C. and at a rate of about 300 Angstroms per minute to about 3000 Angstroms per minute;
• and
• etching a first portion of the polysilicon layer and a second portion of the sacrificial layer using an etchant having a second selectivity of material to polysilicon to form a planarized polysilicon layer, the first selectivity being greater than the second selectivity,
• wherein the etching the first portion of the polysilicon layer and the second portion of the sacrificial layer is performed at a substantially equal rate.

A method of planarizing a polysilicon layer, comprising:

• forming fins on a substrate;
• forming isolation regions on the substrate;
• depositing the polysilicon layer over the fins and the isolation regions;
• depositing an oxide layer on the polysilicon layer;
• chemical mechanical polishing a first portion of the oxide layer using a slurry having a first selectivity of oxide to polysilicon greater than about 1:20, wherein the chemical mechanical polishing is performed at a temperature of about 25° C. and at a rate of about 2000 Angstroms per minute;
• and
• etching a first portion of the polysilicon layer and a second portion of the oxide layer using an etchant having a second selectivity of oxide to polysilicon to planarize the polysilicon layer,
• wherein the etching the first portion of the polysilicon layer and the second portion of the oxide layer is performed at a substantially equal rate.