Crystal evaluation apparatus and crystal evaluation method

• US 5,476,006 A
• Filed: 07/07/1993
• Issued: 12/19/1995
• Est. Priority Date: 07/07/1992
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electronics Corp (Panasonic Holdings Corporation)
• Inventors: Fujii, Shingi, Inoue, Morio, Fuse, Genshu
• Primary Examiner(s): Chilcot, Richard
• Assistant Examiner(s): Dombroske, George M.
• Application Number:
  US08/088,243
• Time in Patent Office: 895 Days
• Field of Search: 73/105, 250/306, 250/307, 250/423 F, 156/626, 436/4, 437/8
• US Class Current: 73/105
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• CPC Class Codes: G01Q 30/14 Liquid environment

Abstract

Crystal evaluation apparatus is disclosed which includes a cell region having an anode and a cathode, a reservoir tank for supplying of an aqueous solution for forming an anodic oxide film in the cell region, a reservoir tank for supplying of an aqueous solution for removing the anodic oxide film and a scanning microprobe microscope having a scanning microprobe, installed inside the cell region. A crystal evaluation method is also disclosed which contains anodic oxidation on a semiconductor substrate, removal of an anodic oxide film developed. The semiconductor substrate is observed with a scanning probe microscope having a scanning microprobe. The oxide film is formed on the semiconductor substrate by the anodic oxidation method and then removed by a mixture of hydrofluoric acid and ammonium fluoride. The anodic oxidation method exerts no or little physical impact on the substrate. The hydrofluoric acid and ammonium fluoride mixture removes selectively only the oxide film so that secondary ion implantation defects are exposed to a surface of the substrate. The shape or configuration of the secondary ion implantation defects is observed with an atomic force microscope having a high resolution on the order of nano meter. Therefore, the shape of the defects on the order of nano meter may be observed. In addition, the distribution of impurity concentration over the surface of the substrate may be measured very accurately.

Claims

1. Crystal evaluation apparatus for evaluating defects at a deep position in a semiconductor device comprising:

(a) anodic oxide film forming cell region including the semiconductor device as an anode and a cathode,

(b) a first solution supply device for forming an anodic oxide film on a surface of the semiconductor device in the cell region by supplying a first aqueous solution,

(c) a second solution supply device for removing the anodic oxide film to an extent to expose the defects at a deep position in the semiconductor device, applying a second aqueous solution and

(d) a scanning microscope having a scanning microprobe, installed inside the anodic oxide film forming cell region, for observing the exposed defects in the semiconductor device.

2. Crystal evaluation apparatus as set forth in claim 1 wherein the scanning probe microscope comprises an atomic force microscope.

3. Crystal evaluation apparatus as set forth in claim 1 further comprising a device for illuminating the cell region with light.

4. Crystal evaluation apparatus as set forth in claim 1 further comprising a device in the cell region for temperature adjustment.

5. Crystal evaluation apparatus comprising:

(a) a cell region including an anode and a cathode,

(b) a device for supplying an aqueous solution for forming an anodic oxide film in the cell region,

(c) a device for supplying an aqueous solution for removing the anodic oxide film,

(d) a scanning microscope having a scanning microprobe, installed inside the cell region, and

(e) a device in the cell region for generating ultrasonic waves.

6. A crystal evaluation method for evaluating defects at a deep position in a semiconductor substrate, comprising the steps of:

(a) forming an anodic oxide film on a semiconductor substrate,

(b) removing the anodic oxide film developed to an extent to expose the defects at a deep position in the semiconductor substrate and

(c) observing the exposed defects in the semiconductor substrate with a scanning probe microscope having a scanning microprobe.

7. A crystal evaluation method as set forth in claim 6 wherein the three-dimensional state of the defects present in the semiconductor substrate is observed during the observation step.

8. A crystal evaluation method as set forth in claim 6 wherein the distribution of the impurity concentration over the semiconductor substrate is observed during the observing step.

9. A crystal evaluation method as set forth in claim 6 wherein the scanning probe microscope with the scanning microprobe comprises an atomic force microscope.

10. A method for evaluating defects at a deep position in a semiconductor substrate, as set forth in claim 6, wherein the defects include ion implantation defects and the anode oxide film is removed to expose the ion implantation defects.

11. A crystal evaluation method as set forth in claim 6 wherein a mixture of hydrofluoric acid and ammonium fluoride is used to within a cell which contains an atomic power microscope microprobe for removing the anodic oxide film.

12. A crystal evaluation method as set forth in claim 6 wherein a mixed solution of N-Methylacetamide, potassium oxalate and water is used as an anodic oxidizing solution.

13. A crystal evaluation method as set forth in claim 6 wherein a constant current is supplied to form the anodic oxide film.

14. A method for measuring impurity concentration distribution over a semiconductor substrate having an impurity introduction layer, comprising the steps of:

(a) forming an oxide film at a cleavage plane of the semiconductor substrate so that the thickness of the oxide film developed is proportional to the concentration of an impurity introduced,

(b) removing selectively only the oxide film to an extent to retreat and expose the cleavage plane of the semiconductor substrate in proportion to the concentration of the impurity introduced, and

(c) observing the distribution of the concentration of the impurity introduced by observing the shape of the retreated and exposed cleavage plane of the semiconductor substrate with an atomic force microscope.

15. Crystal evaluation apparatus for evaluating defects at a deep position in a semiconductor device comprising:

(a) anodic oxide film forming cell region including the semiconductor device as an anode and a cathode,

(b) a first solution supply device for forming an anodic oxide film on a surface of the semiconductor device in the cell region by supplying a first aqueous solution,

(c) a second solution supply device for removing the anodic oxide film to an extent to expose the defects at a deep position in the semiconductor device, by supplying a second aqueous solution and

(d) a scanning microscope having a scanning microprobe, installed inside the anodic oxide film forming cell region, wherein force of repulsion is measured between the microprobe installed on a cantilever and the semiconductor device, with laser light incident on the cantilever and reflecting from the cantilever, for observing the exposed defects in the semiconductor device, and

(e) a display providing a display of the state of the semiconductor device as an three-dimensional image.

16. A crystal evaluation method for evaluating defects at a deep position in a semiconductor substrate, comprising the steps of:

(a) forming an anodic oxide film on the semiconductor substrate,

(b) removing the anodic oxide film developed,

(c) repeating continuously the above steps (a) and (b) to an extent to expose the defects at a deep position in the semiconductor substrate and

(d) observing the exposed defects in the semiconductor substrate with a scanning probe microscope having a scanning microprobe.