Method for forming a spacer with a prograde profile

A method for forming spacers having a prograde profile in the manufacture of a semiconductor device, said method comprising the steps of:

• (a) providing a semiconductor substrate having raised structures thereon, said raised structures having top and lateral surfaces;
• (b) depositing conformably over said substrate and said raised structures a layer of undoped silicon dioxide;
• (c) depositing conformably over said layer of undoped silicon dioxide a layer of boron doped silicon dioxide, wherein the layer of boron doped silicon dioxide has a thickness in a range from about 50 Angstroms to less than 1500 Angstroms;
• and
• (d) reflowing said layer of boron doped silicon dioxide;
• wherein the portions of said layer of undoped silicon dioxide and said layer of boron doped silicon dioxide covering the lateral surfaces of said raised structures constitute spacers laterally enclosing said raised structures, and wherein said step of reflowing said layer of boron doped silicon dioxide results in said spacers having laterally outward facing surfaces sloping laterally outward from the top surface of said raised structures downward.

A method for forming spacers having a prograde profile in the manufacture of a semiconductor device, said method comprising the steps of:

• (a) providing a semiconductor substrate having gate stacks thereon, said gate stacks having top and lateral surfaces;
• (b) depositing conformably over said substrate and said gate stacks a layer of undoped silicon dioxide by performing steps comprising:
• (i) placing the substrate in a process chamber;
• (ii) drawing a vacuum in the process chamber and maintaining the pressure in the process chamber at a pressure in a range of about 10 to 500 Torr;
• (iii) maintaining the substrate at a temperature in a range of about 300.degree. to 50.degree. C.;
• (iv) flowing a carrier gas at a rate in a range of about 2000 to 5000 sccm through a bubbler having TEOS therein and into the process chamber while maintaining the TEOS in said bubbler at a temperature in a range of about 45.degree. to 55.degree. C.;
• (v) flowing ozone into said process chamber at a concentration in a range of about 5 to 20% by weight;
• and
• (vi) depositing the layer of undoped silicon dioxide on said substrate having a thickness in a range of about 800 to 1000 Angstroms;
• (c) depositing conformably over said layer of undoped silicon dioxide a layer of boron doped silicon dioxide having a thickness in a range from about 50 Angstroms to less than 1500 Angstroms;
• and
• (d) reflowing said layer of boron doped silicon dioxide;
• wherein the portions of said layer of undoped silicon dioxide and said layer of boron doped silicon dioxide covering the lateral surfaces of said gate stacks constitute spacers laterally enclosing said gate stacks, and wherein said step of reflowing said layer of boron doped silicon dioxide results in said spacers having laterally outward facing surfaces sloping laterally outward from the top surface of said gate stacks downward.

A method for preventing the formation of stringers at the base of spacers in the manufacture of a semiconductor device, said method comprising the steps of:

• (a) providing a semiconductor substrate having raised structures thereon, said raised structures having top and lateral surfaces;
• (b) depositing conformably over said substrate and said raised structures a layer of dielectric spacer material;
• (c) depositing conformably over said layer of dielectric spacer material a layer of compatible material compatible with said dielectric spacer material and having lower viscosity at high temperature than said dielectric spacer material, wherein the layer of compatible material has a thickness of about 500 Angstroms;
• and
• (d) reflowing said layer of compatible material such that said layer of compatible material at said lateral surfaces of said raised structures is thicker in a lateral direction near the bottom of said raised structures than near the top of said raised structures.

A method for forming spacers having a prograde profile in the manufacture of a semiconductor device, said method comprising the steps of:

• (a) providing a semiconductor substrate having raised structures thereon, said raised structures having top and lateral surfaces;
• (b) depositing conformably over said substrate and said raised structures a layer of undoped silicon dioxide;
• (c) depositing conformably over said layer of undoped silicon dioxide a layer of boron doped silicon dioxide having a thickness of about 500 Angstroms;
• and
• (d) reflowing said layer of boron doped silicon dioxide;
• wherein the portions of said layer of undoped silicon dioxide and said layer of boron doped silicon dioxide covering the lateral surfaces of said raised structures constitute spacers laterally enclosing said raised structures, and wherein said step of reflowing said layer of boron doped silicon dioxide results in said spacers having laterally outward facing surfaces sloping laterally outward from the top surface of said raised structures downward.

A method for forming spacers having a prograde profile in the manufacture of a semiconductor device, said method comprising the steps of:

• (a) providing a semiconductor substrate having gate stacks thereon, said gate stacks having top and lateral surfaces;
• (b) depositing conformably over said substrate and said gate stacks a layer of undoped silicon dioxide by performing steps comprising:
• (i) placing the substrate in a process chamber;
• (ii) drawing a vacuum in the process chamber and maintaining the pressure in the process chamber at a pressure in a range of about 10 to 500 Torr;
• (iii) maintaining the substrate at a temperature in a range of about 300.degree. to 500.degree. C.;
• (iv) flowing a carrier gas at a rate in a range of about 2000 to 5000 sccm through a bubbler having TEOS therein and into the process chamber while maintaining the TEOS in said bubbler at a temperature in a range of about 45.degree. to 55.degree. C.;
• (v) flowing ozone into said process chamber at a concentration in a range of about 5 to 20% by weight;
• and
• (vi) depositing the layer of undoped silicon dioxide on said substrate having a thickness in a range of about 800 to 1000 Angstroms;
• (c) depositing conformably over said layer of undoped silicon dioxide a layer of boron doped silicon dioxide having a thickness of about 500 Angstroms;
• and
• (d) reflowing said layer of boron doped silicon dioxide;
• wherein the portions of said layer of undoped silicon dioxide and said layer of boron doped silicon dioxide covering the lateral surfaces of said gate stacks constitute spacers laterally enclosing said gate stacks, and wherein said step of reflowing said layer of boron doped silicon dioxide results in said spacers having laterally outward facing surfaces sloping laterally outward from the top surface of said gate stacks downward.